| Message ID | 20240527122216.244443-1-perex@perex.cz (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [RFC,v2] ALSA: compress_offload: introduce passthrough operation mode | expand |
On Mon, May 27, 2024 at 8:23 PM Jaroslav Kysela <perex@perex.cz> wrote: > > There is a requirement to expose the audio hardware that accelerates various > tasks for user space such as sample rate converters, compressed > stream decoders, etc. > > This is description for the API extension for the compress ALSA API which > is able to handle "tasks" that are not bound to real-time operations > and allows for the serialization of operations. > > For details, refer to "compress-passthrough.rst" document. > > Note: This code is RFC (not tested, just to clearify the API requirements). > My goal is to add a test (loopback) driver and add a support to tinycompress > library in the next step. > > Cc: Mark Brown <broonie@kernel.org> > Cc: Shengjiu Wang <shengjiu.wang@gmail.com> > Cc: Nicolas Dufresne <nicolas@ndufresne.ca> > Cc: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com> > Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> > Cc: Vinod Koul <vkoul@kernel.org> > Signed-off-by: Jaroslav Kysela <perex@perex.cz> > > --- > v1..v2: > - fix some documentation typos (thanks Amadeusz Sławiński) > - fix memdup_user() error handling (thanks Takashi) > - use one state variable instead multiple (thanks Takashi) > - handle task limit (set to 64 - mentioned in documentation, NIY) > - fix file release (free all tasks) > --- > .../sound/designs/compress-passthrough.rst | 125 +++++++ > include/sound/compress_driver.h | 32 ++ > include/uapi/sound/compress_offload.h | 51 ++- > sound/core/Kconfig | 4 + > sound/core/compress_offload.c | 334 +++++++++++++++++- > 5 files changed, 537 insertions(+), 9 deletions(-) > create mode 100644 Documentation/sound/designs/compress-passthrough.rst > > diff --git a/Documentation/sound/designs/compress-passthrough.rst b/Documentation/sound/designs/compress-passthrough.rst > new file mode 100644 > index 000000000000..975462500c33 > --- /dev/null > +++ b/Documentation/sound/designs/compress-passthrough.rst > @@ -0,0 +1,125 @@ > +================================= > +ALSA Co-processor Passthrough API > +================================= > + > +Jaroslav Kysela <perex@perex.cz> > + > + > +Overview > +======== > + > +There is a requirement to expose the audio hardware that accelerates various > +tasks for user space such as sample rate converters, compressed > +stream decoders, etc. > + > +This is description for the API extension for the compress ALSA API which > +is able to handle "tasks" that are not bound to real-time operations > +and allows for the serialization of operations. > + > +Requirements > +============ > + > +The main requirements are: > + > +- serialization of multiple tasks for user space to allow multiple > + operations without user space intervention > + > +- separate buffers (input + output) for each operation > + > +- expose buffers using mmap to user space > + > +- signal user space when the task is finished (standard poll mechanism) > + > +Design > +====== > + > +A new direction SND_COMPRESS_PASSTHROUGH is introduced to identify > +the passthrough API. > + > +The API extension shares device enumeration and parameters handling from > +the main compressed API. All other realtime streaming ioctls are deactivated > +and a new set of task related ioctls are introduced. The standard > +read/write/mmap I/O operations are not supported in the passthrough device. > + > +Device ("stream") state handling is reduced to OPEN/SETUP. All other > +states are not available for the passthrough mode. > + > +Data I/O mechanism is using standard dma-buf interface with all advantages > +like mmap, standard I/O, buffer sharing etc. One buffer is used for the > +input data and second (separate) buffer is used for the output data. Each task > +have separate I/O buffers. > + > +For the buffering parameters, the fragments means a limit of allocated tasks > +for given device. The fragment_size limits the input buffer size for the given > +device. The output buffer size is determined by the driver (may be different > +from the input buffer size). > + > +State Machine > +============= > + > +The passthrough audio stream state machine is described below : > + > + +----------+ > + | | > + | OPEN | > + | | > + +----------+ > + | > + | > + | compr_set_params() > + | > + v > + all passthrough task ops +----------+ > + +------------------------------------| | > + | | SETUP | > + | | > + | +----------+ > + | | > + +------------------------------------------+ > + > + > +Passthrough operations (ioctls) > +=============================== > + > +CREATE > +------ > +Creates a set of input/output buffers. The input buffer size is > +fragment_size. Allocates unique seqno. > + > +The hardware drivers allocate internal 'struct dma_buf' for both input and > +output buffers (using 'dma_buf_export()' function). The anonymous > +file descriptors for those buffers are passed to user space. > + Audio data is always separated into a lot of periods. so does this mean that the call sequence is "CREATE" (user fill period data to buffer ) "START" -> "CREATE" (user fill period data to buffer )"START" -> "CREATE" (user fill period data to buffer )"START".... ? Will this cause memory fragmentation? How can the user get each output? Or does this mean the sequence should be: "CREATE" (user space fill period data to buffer ) "START" "STOP" : if the task is running, stop it there is no output generated? "STATUS": polling the status to check the task finished for every task? then another loop for each period? best regards Shengjiu Wang > +FREE > +---- > +Free a set of input/output buffers. If a task is active, the stop > +operation is executed before. If seqno is zero, operation is executed for all > +tasks. > + > +START > +----- > +Starts (queues) a task. There are two cases of the task start - right after > +the task is created. In this case, origin_seqno must be zero. > +The second case is for reusing of already finished task. The origin_seqno > +must identify the task to be reused. In both cases, a new seqno value > +is allocated and returned to user space. > + > +The prerequisite is that application filled input dma buffer with > +new source data and set input_size to pass the real data size to the driver. > + > +The order of data processing is preserved (first started job must be > +finished at first). > + > +STOP > +---- > +Stop (dequeues) a task. If seqno is zero, operation is executed for all > +tasks. > + > +STATUS > +------ > +Obtain the task status (active, finished). Also, the driver will set > +the real output data size (valid area in the output buffer). > + > +Credits > +======= > +- ... > diff --git a/include/sound/compress_driver.h b/include/sound/compress_driver.h > index bcf872c17dd3..2884b1e7955d 100644 > --- a/include/sound/compress_driver.h > +++ b/include/sound/compress_driver.h > @@ -19,6 +19,22 @@ > > struct snd_compr_ops; > > +/** > + * struct snd_compr_task_runtime: task runtime description > + * > + */ > +struct snd_compr_task_runtime { > + struct list_head list; > + struct dma_buf *input; > + struct dma_buf *output; > + u64 seqno; > + u64 input_size; > + u64 output_size; > + u8 state; > + void *private_value; > +}; > + > + > /** > * struct snd_compr_runtime: runtime stream description > * @state: stream state > @@ -54,6 +70,11 @@ struct snd_compr_runtime { > dma_addr_t dma_addr; > size_t dma_bytes; > struct snd_dma_buffer *dma_buffer_p; > + > + u32 active_tasks; > + u32 total_tasks; > + u64 task_seqno; > + struct list_head tasks; > }; > > /** > @@ -132,6 +153,12 @@ struct snd_compr_ops { > struct snd_compr_caps *caps); > int (*get_codec_caps) (struct snd_compr_stream *stream, > struct snd_compr_codec_caps *codec); > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > + int (*task_create) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); > + int (*task_start) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); > + int (*task_stop) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); > + int (*task_free) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); > +#endif > }; > > /** > @@ -242,4 +269,9 @@ int snd_compr_free_pages(struct snd_compr_stream *stream); > int snd_compr_stop_error(struct snd_compr_stream *stream, > snd_pcm_state_t state); > > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > +void snd_compr_task_finished(struct snd_compr_stream *stream, > + struct snd_compr_task_runtime *task); > +#endif > + > #endif > diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h > index d185957f3fe0..5fed1979522b 100644 > --- a/include/uapi/sound/compress_offload.h > +++ b/include/uapi/sound/compress_offload.h > @@ -1,4 +1,4 @@ > -/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > + /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > /* > * compress_offload.h - compress offload header definations > * > @@ -14,7 +14,7 @@ > #include <sound/compress_params.h> > > > -#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 2, 0) > +#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 3, 0) > /** > * struct snd_compressed_buffer - compressed buffer > * @fragment_size: size of buffer fragment in bytes > @@ -68,7 +68,8 @@ struct snd_compr_avail { > > enum snd_compr_direction { > SND_COMPRESS_PLAYBACK = 0, > - SND_COMPRESS_CAPTURE > + SND_COMPRESS_CAPTURE, > + SND_COMPRESS_PASSTHROUGH > }; > > /** > @@ -127,6 +128,42 @@ struct snd_compr_metadata { > __u32 value[8]; > } __attribute__((packed, aligned(4))); > > +/** > + * struct snd_compr_task - task primitive for non-realtime operation > + * @seqno: sequence number (task identifier) > + * @origin_seqno: previous sequence number (task identifier) - for reuse > + * @input_fd: data input file descriptor (dma-buf) > + * @output_fd: data output file descriptor (dma-buf) > + * @input_size: filled data in bytes (from caller, must not exceed fragment size) > + */ > +struct snd_compr_task { > + __u64 seqno; > + __u64 origin_seqno; > + int input_fd; > + int output_fd; > + __u64 input_size; > + __u8 reserved[16]; > +} __attribute__((packed, aligned(4))); > + > +enum snd_compr_state { > + SND_COMPRESS_TASK_STATE_IDLE = 0, > + SND_COMPRESS_TASK_STATE_ACTIVE, > + SND_COMPRESS_TASK_STATE_FINISHED > +}; > + > +/** > + * struct snd_compr_task_status - task status > + * @seqno: sequence number (task identifier) > + * @output_size: filled data in bytes (from driver) > + * @state: actual task state (SND_COMPRESS_TASK_STATE_*) > + */ > +struct snd_compr_task_status { > + __u64 seqno; > + __u64 output_size; > + __u8 state; > + __u8 reserved[15]; > +} __attribute__((packed, aligned(4))); > + > /* > * compress path ioctl definitions > * SNDRV_COMPRESS_GET_CAPS: Query capability of DSP > @@ -164,6 +201,14 @@ struct snd_compr_metadata { > #define SNDRV_COMPRESS_DRAIN _IO('C', 0x34) > #define SNDRV_COMPRESS_NEXT_TRACK _IO('C', 0x35) > #define SNDRV_COMPRESS_PARTIAL_DRAIN _IO('C', 0x36) > + > + > +#define SNDRV_COMPRESS_TASK_CREATE _IOWR('C', 0x60, struct snd_compr_task) > +#define SNDRV_COMPRESS_TASK_FREE _IOW('C', 0x61, __u64) > +#define SNDRV_COMPRESS_TASK_START _IOWR('C', 0x62, struct snd_compr_task) > +#define SNDRV_COMPRESS_TASK_STOP _IOW('C', 0x63, __u64) > +#define SNDRV_COMPRESS_TASK_STATUS _IOWR('C', 0x68, struct snd_compr_task_status) > + > /* > * TODO > * 1. add mmap support > diff --git a/sound/core/Kconfig b/sound/core/Kconfig > index 8077f481d84f..3541fe6d477f 100644 > --- a/sound/core/Kconfig > +++ b/sound/core/Kconfig > @@ -59,6 +59,10 @@ config SND_CORE_TEST > config SND_COMPRESS_OFFLOAD > tristate > > +config SND_COMPRESS_PASSTHROUGH > + select DMA_BUF > + tristate > + > config SND_JACK > bool > > diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c > index f0008fa2d839..da048e61c574 100644 > --- a/sound/core/compress_offload.c > +++ b/sound/core/compress_offload.c > @@ -24,6 +24,7 @@ > #include <linux/types.h> > #include <linux/uio.h> > #include <linux/uaccess.h> > +#include <linux/dma-buf.h> > #include <linux/module.h> > #include <linux/compat.h> > #include <sound/core.h> > @@ -54,6 +55,12 @@ struct snd_compr_file { > > static void error_delayed_work(struct work_struct *work); > > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > +static void snd_compr_task_free_all(struct snd_compr_stream *stream); > +#else > +static inline void snd_compr_task_free_all(struct snd_compr_stream *stream) { } > +#endif > + > /* > * a note on stream states used: > * we use following states in the compressed core > @@ -85,6 +92,8 @@ static int snd_compr_open(struct inode *inode, struct file *f) > dirn = SND_COMPRESS_PLAYBACK; > else if ((f->f_flags & O_ACCMODE) == O_RDONLY) > dirn = SND_COMPRESS_CAPTURE; > + else if ((f->f_flags & O_ACCMODE) == O_RDWR) > + dirn = SND_COMPRESS_PASSTHROUGH; > else > return -EINVAL; > > @@ -154,6 +163,8 @@ static int snd_compr_free(struct inode *inode, struct file *f) > break; > } > > + snd_compr_task_free_all(&data->stream); > + > data->stream.ops->free(&data->stream); > if (!data->stream.runtime->dma_buffer_p) > kfree(data->stream.runtime->buffer); > @@ -226,6 +237,9 @@ snd_compr_ioctl_avail(struct snd_compr_stream *stream, unsigned long arg) > struct snd_compr_avail ioctl_avail; > size_t avail; > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > + return -EBADFD; > + > avail = snd_compr_calc_avail(stream, &ioctl_avail); > ioctl_avail.avail = avail; > > @@ -287,6 +301,8 @@ static ssize_t snd_compr_write(struct file *f, const char __user *buf, > return -EFAULT; > > stream = &data->stream; > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > + return -EBADFD; > guard(mutex)(&stream->device->lock); > /* write is allowed when stream is running or has been steup */ > switch (stream->runtime->state) { > @@ -336,6 +352,8 @@ static ssize_t snd_compr_read(struct file *f, char __user *buf, > return -EFAULT; > > stream = &data->stream; > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > + return -EBADFD; > guard(mutex)(&stream->device->lock); > > /* read is allowed when stream is running, paused, draining and setup > @@ -385,6 +403,8 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) > { > struct snd_compr_file *data = f->private_data; > struct snd_compr_stream *stream; > + struct snd_compr_runtime *runtime; > + struct snd_compr_task_runtime *task; > size_t avail; > __poll_t retval = 0; > > @@ -392,6 +412,7 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) > return EPOLLERR; > > stream = &data->stream; > + runtime = stream->runtime; > > guard(mutex)(&stream->device->lock); > > @@ -405,6 +426,18 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) > > poll_wait(f, &stream->runtime->sleep, wait); > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) { > + if (runtime->fragments > runtime->active_tasks) > + retval |= EPOLLOUT | EPOLLWRNORM; > + task = list_first_entry_or_null(&runtime->tasks, > + struct snd_compr_task_runtime, > + list); > + if (task && task->state == SND_COMPRESS_TASK_STATE_FINISHED) > + retval |= EPOLLIN | EPOLLRDNORM; > + return retval; > + } > + > + > avail = snd_compr_get_avail(stream); > pr_debug("avail is %ld\n", (unsigned long)avail); > /* check if we have at least one fragment to fill */ > @@ -521,6 +554,9 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream, > unsigned int buffer_size; > void *buffer = NULL; > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > + goto params; > + > buffer_size = params->buffer.fragment_size * params->buffer.fragments; > if (stream->ops->copy) { > buffer = NULL; > @@ -543,18 +579,30 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream, > if (!buffer) > return -ENOMEM; > } > - stream->runtime->fragment_size = params->buffer.fragment_size; > - stream->runtime->fragments = params->buffer.fragments; > + > stream->runtime->buffer = buffer; > stream->runtime->buffer_size = buffer_size; > +params: > + stream->runtime->fragment_size = params->buffer.fragment_size; > + stream->runtime->fragments = params->buffer.fragments; > return 0; > } > > -static int snd_compress_check_input(struct snd_compr_params *params) > +static int > +snd_compress_check_input(struct snd_compr_stream *stream, struct snd_compr_params *params) > { > + u32 max_fragments; > + > /* first let's check the buffer parameter's */ > - if (params->buffer.fragment_size == 0 || > - params->buffer.fragments > U32_MAX / params->buffer.fragment_size || > + if (params->buffer.fragment_size == 0) > + return -EINVAL; > + > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > + max_fragments = 64; /* safe value */ > + else > + max_fragments = U32_MAX / params->buffer.fragment_size; > + > + if (params->buffer.fragments > max_fragments || > params->buffer.fragments == 0) > return -EINVAL; > > @@ -583,7 +631,7 @@ snd_compr_set_params(struct snd_compr_stream *stream, unsigned long arg) > if (IS_ERR(params)) > return PTR_ERR(no_free_ptr(params)); > > - retval = snd_compress_check_input(params); > + retval = snd_compress_check_input(stream, params); > if (retval) > return retval; > > @@ -939,6 +987,259 @@ static int snd_compr_partial_drain(struct snd_compr_stream *stream) > return snd_compress_wait_for_drain(stream); > } > > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > + > +static struct snd_compr_task_runtime * > + snd_compr_find_task(struct snd_compr_stream *stream, __u64 seqno) > +{ > + struct snd_compr_task_runtime *task; > + > + list_for_each_entry(task, &stream->runtime->tasks, list) { > + if (task->seqno == seqno) > + return task; > + } > + return NULL; > +} > + > +static void snd_compr_task_free(struct snd_compr_task_runtime *task) > +{ > + if (task->output) > + dma_buf_put(task->output); > + if (task->input) > + dma_buf_put(task->input); > + kfree(task); > +} > + > +static u64 snd_compr_seqno_next(struct snd_compr_stream *stream) > +{ > + u64 seqno = ++stream->runtime->task_seqno; > + if (seqno == 0) > + seqno = ++stream->runtime->task_seqno; > + return seqno; > +} > + > +static int snd_compr_task_new(struct snd_compr_stream *stream, struct snd_compr_task *utask) > +{ > + struct snd_compr_task_runtime *task; > + int retval; > + > + if (stream->runtime->total_tasks >= stream->runtime->fragments) > + return -EBUSY; > + if (utask->origin_seqno != 0 || utask->input_size != 0) > + return -EINVAL; > + task = kzalloc(sizeof(*task), GFP_KERNEL); > + if (task == NULL) > + return -ENOMEM; > + task->seqno = snd_compr_seqno_next(stream); > + task->input_size = utask->input_size; > + retval = stream->ops->task_create(stream, task); > + if (retval < 0) > + goto cleanup; > + utask->input_fd = dma_buf_fd(task->input, O_WRONLY|O_CLOEXEC); > + if (utask->input_fd < 0) { > + retval = utask->input_fd; > + goto cleanup; > + } > + utask->output_fd = dma_buf_fd(task->output, O_RDONLY|O_CLOEXEC); > + if (utask->output_fd < 0) { > + retval = utask->output_fd; > + goto cleanup; > + } > + list_add_tail(&task->list, &stream->runtime->tasks); > + stream->runtime->total_tasks++; > + return 0; > +cleanup: > + snd_compr_task_free(task); > + return retval; > +} > + > +static int snd_compr_task_create(struct snd_compr_stream *stream, unsigned long arg) > +{ > + struct snd_compr_task *task __free(kfree) = NULL; > + int retval; > + > + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) > + return -EPERM; > + task = memdup_user((void __user *)arg, sizeof(*task)); > + if (IS_ERR(task)) > + return PTR_ERR(no_free_ptr(task)); > + retval = snd_compr_task_new(stream, task); > + if (retval >= 0) > + if (copy_to_user((void __user *)arg, task, sizeof(*task))) > + retval = -EFAULT; > + return retval; > +} > + > +static int snd_compr_task_start_prepare(struct snd_compr_task_runtime *task, > + struct snd_compr_task *utask) > +{ > + if (task == NULL) > + return -EINVAL; > + if (task->state >= SND_COMPRESS_TASK_STATE_FINISHED) > + return -EBUSY; > + if (utask->input_size > task->input->size) > + return -EINVAL; > + task->input_size = utask->input_size; > + task->state = SND_COMPRESS_TASK_STATE_IDLE; > + return 0; > +} > + > +static int snd_compr_task_start(struct snd_compr_stream *stream, struct snd_compr_task *utask) > +{ > + struct snd_compr_task_runtime *task; > + int retval; > + > + if (utask->origin_seqno > 0) { > + task = snd_compr_find_task(stream, utask->seqno); > + retval = snd_compr_task_start_prepare(task, utask); > + if (retval < 0) > + return retval; > + task->seqno = utask->seqno = snd_compr_seqno_next(stream); > + utask->origin_seqno = 0; > + list_move_tail(&task->list, &stream->runtime->tasks); > + } else { > + task = snd_compr_find_task(stream, utask->seqno); > + if (task && task->state != SND_COMPRESS_TASK_STATE_IDLE) > + return -EBUSY; > + retval = snd_compr_task_start_prepare(task, utask); > + if (retval < 0) > + return retval; > + } > + retval = stream->ops->task_start(stream, task); > + if (retval >= 0) { > + task->state = SND_COMPRESS_TASK_STATE_ACTIVE; > + stream->runtime->active_tasks++; > + } > + return retval; > +} > + > +static int snd_compr_task_start_ioctl(struct snd_compr_stream *stream, unsigned long arg) > +{ > + struct snd_compr_task *task __free(kfree) = NULL; > + int retval; > + > + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) > + return -EPERM; > + task = memdup_user((void __user *)arg, sizeof(*task)); > + if (IS_ERR(task)) > + return PTR_ERR(no_free_ptr(task)); > + retval = snd_compr_task_start(stream, task); > + if (retval >= 0) > + if (copy_to_user((void __user *)arg, task, sizeof(*task))) > + retval = -EFAULT; > + return retval; > +} > + > +static void snd_compr_task_stop_one(struct snd_compr_stream *stream, > + struct snd_compr_task_runtime *task) > +{ > + if (task->state != SND_COMPRESS_TASK_STATE_ACTIVE) > + return; > + stream->ops->task_stop(stream, task); > + if (!snd_BUG_ON(stream->runtime->active_tasks == 0)) > + stream->runtime->active_tasks--; > + list_move_tail(&task->list, &stream->runtime->tasks); > + task->state = SND_COMPRESS_TASK_STATE_IDLE; > +} > + > +static void snd_compr_task_free_one(struct snd_compr_stream *stream, > + struct snd_compr_task_runtime *task) > +{ > + snd_compr_task_stop_one(stream, task); > + stream->ops->task_free(stream, task); > + list_del(&task->list); > + snd_compr_task_free(task); > + stream->runtime->total_tasks--; > +} > + > +static void snd_compr_task_free_all(struct snd_compr_stream *stream) > +{ > + struct snd_compr_task_runtime *task; > + > + list_for_each_entry(task, &stream->runtime->tasks, list) > + snd_compr_task_free_one(stream, task); > +} > + > +typedef void (*snd_compr_seq_func_t)(struct snd_compr_stream *stream, > + struct snd_compr_task_runtime *task); > + > +static int snd_compr_task_seq(struct snd_compr_stream *stream, unsigned long arg, > + snd_compr_seq_func_t fcn) > +{ > + struct snd_compr_task_runtime *task; > + __u64 seqno; > + int retval; > + > + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) > + return -EPERM; > + retval = get_user(seqno, (__u64 __user *)arg); > + if (retval < 0) > + return retval; > + retval = 0; > + if (seqno == 0) { > + list_for_each_entry(task, &stream->runtime->tasks, list) > + fcn(stream, task); > + } else { > + task = snd_compr_find_task(stream, seqno); > + if (task == NULL) { > + retval = -EINVAL; > + } else { > + fcn(stream, task); > + } > + } > + return retval; > +} > + > +static int snd_compr_task_status(struct snd_compr_stream *stream, > + struct snd_compr_task_status *status) > +{ > + struct snd_compr_task_runtime *task; > + > + task = snd_compr_find_task(stream, status->seqno); > + if (task == NULL) > + return -EINVAL; > + status->output_size = task->output_size; > + status->state = task->state; > + return 0; > +} > + > +static int snd_compr_task_status_ioctl(struct snd_compr_stream *stream, unsigned long arg) > +{ > + struct snd_compr_task_status *status __free(kfree) = NULL; > + int retval; > + > + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) > + return -EPERM; > + status = memdup_user((void __user *)arg, sizeof(*status)); > + if (IS_ERR(status)) > + return PTR_ERR(no_free_ptr(status)); > + retval = snd_compr_task_status(stream, status); > + if (retval >= 0) > + if (copy_to_user((void __user *)arg, status, sizeof(*status))) > + retval = -EFAULT; > + return retval; > +} > + > +/** > + * snd_compr_task_finished: Notify that the task was finished > + * @stream: pointer to stream > + * @task: runtime task structure > + * > + * Set the finished task state and notify waiters. > + */ > +void snd_compr_task_finished(struct snd_compr_stream *stream, > + struct snd_compr_task_runtime *task) > +{ > + guard(mutex)(&stream->device->lock); > + if (!snd_BUG_ON(stream->runtime->active_tasks == 0)) > + stream->runtime->active_tasks--; > + task->state = SND_COMPRESS_TASK_STATE_FINISHED; > + wake_up(&stream->runtime->sleep); > +} > +EXPORT_SYMBOL(snd_compr_task_finished); > + > +#endif /* CONFIG_COMPRESS_PASSTHROUGH */ > + > static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg) > { > struct snd_compr_file *data = f->private_data; > @@ -968,6 +1269,27 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg) > return snd_compr_set_metadata(stream, arg); > case _IOC_NR(SNDRV_COMPRESS_GET_METADATA): > return snd_compr_get_metadata(stream, arg); > + } > + > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) { > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > + switch (_IOC_NR(cmd)) { > + case _IOC_NR(SNDRV_COMPRESS_TASK_CREATE): > + return snd_compr_task_create(stream, arg); > + case _IOC_NR(SNDRV_COMPRESS_TASK_FREE): > + return snd_compr_task_seq(stream, arg, snd_compr_task_free_one); > + case _IOC_NR(SNDRV_COMPRESS_TASK_START): > + return snd_compr_task_start_ioctl(stream, arg); > + case _IOC_NR(SNDRV_COMPRESS_TASK_STOP): > + return snd_compr_task_seq(stream, arg, snd_compr_task_stop_one); > + case _IOC_NR(SNDRV_COMPRESS_TASK_STATUS): > + return snd_compr_task_status_ioctl(stream, arg); > + } > +#endif > + return -ENOTTY; > + } > + > + switch (_IOC_NR(cmd)) { > case _IOC_NR(SNDRV_COMPRESS_TSTAMP): > return snd_compr_tstamp(stream, arg); > case _IOC_NR(SNDRV_COMPRESS_AVAIL): > -- > 2.45.1 >
On Tue, May 28, 2024 at 7:14 PM Shengjiu Wang <shengjiu.wang@gmail.com> wrote: > > On Mon, May 27, 2024 at 8:23 PM Jaroslav Kysela <perex@perex.cz> wrote: > > > > There is a requirement to expose the audio hardware that accelerates various > > tasks for user space such as sample rate converters, compressed > > stream decoders, etc. > > > > This is description for the API extension for the compress ALSA API which > > is able to handle "tasks" that are not bound to real-time operations > > and allows for the serialization of operations. > > > > For details, refer to "compress-passthrough.rst" document. > > > > Note: This code is RFC (not tested, just to clearify the API requirements). > > My goal is to add a test (loopback) driver and add a support to tinycompress > > library in the next step. > > > > Cc: Mark Brown <broonie@kernel.org> > > Cc: Shengjiu Wang <shengjiu.wang@gmail.com> > > Cc: Nicolas Dufresne <nicolas@ndufresne.ca> > > Cc: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com> > > Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> > > Cc: Vinod Koul <vkoul@kernel.org> > > Signed-off-by: Jaroslav Kysela <perex@perex.cz> > > > > --- > > v1..v2: > > - fix some documentation typos (thanks Amadeusz Sławiński) > > - fix memdup_user() error handling (thanks Takashi) > > - use one state variable instead multiple (thanks Takashi) > > - handle task limit (set to 64 - mentioned in documentation, NIY) > > - fix file release (free all tasks) > > --- > > .../sound/designs/compress-passthrough.rst | 125 +++++++ > > include/sound/compress_driver.h | 32 ++ > > include/uapi/sound/compress_offload.h | 51 ++- > > sound/core/Kconfig | 4 + > > sound/core/compress_offload.c | 334 +++++++++++++++++- > > 5 files changed, 537 insertions(+), 9 deletions(-) > > create mode 100644 Documentation/sound/designs/compress-passthrough.rst > > > > diff --git a/Documentation/sound/designs/compress-passthrough.rst b/Documentation/sound/designs/compress-passthrough.rst > > new file mode 100644 > > index 000000000000..975462500c33 > > --- /dev/null > > +++ b/Documentation/sound/designs/compress-passthrough.rst > > @@ -0,0 +1,125 @@ > > +================================= > > +ALSA Co-processor Passthrough API > > +================================= > > + > > +Jaroslav Kysela <perex@perex.cz> > > + > > + > > +Overview > > +======== > > + > > +There is a requirement to expose the audio hardware that accelerates various > > +tasks for user space such as sample rate converters, compressed > > +stream decoders, etc. > > + > > +This is description for the API extension for the compress ALSA API which > > +is able to handle "tasks" that are not bound to real-time operations > > +and allows for the serialization of operations. > > + > > +Requirements > > +============ > > + > > +The main requirements are: > > + > > +- serialization of multiple tasks for user space to allow multiple > > + operations without user space intervention > > + > > +- separate buffers (input + output) for each operation > > + > > +- expose buffers using mmap to user space > > + > > +- signal user space when the task is finished (standard poll mechanism) > > + > > +Design > > +====== > > + > > +A new direction SND_COMPRESS_PASSTHROUGH is introduced to identify > > +the passthrough API. > > + > > +The API extension shares device enumeration and parameters handling from > > +the main compressed API. All other realtime streaming ioctls are deactivated > > +and a new set of task related ioctls are introduced. The standard > > +read/write/mmap I/O operations are not supported in the passthrough device. > > + > > +Device ("stream") state handling is reduced to OPEN/SETUP. All other > > +states are not available for the passthrough mode. > > + > > +Data I/O mechanism is using standard dma-buf interface with all advantages > > +like mmap, standard I/O, buffer sharing etc. One buffer is used for the > > +input data and second (separate) buffer is used for the output data. Each task > > +have separate I/O buffers. > > + > > +For the buffering parameters, the fragments means a limit of allocated tasks > > +for given device. The fragment_size limits the input buffer size for the given > > +device. The output buffer size is determined by the driver (may be different > > +from the input buffer size). > > + > > +State Machine > > +============= > > + > > +The passthrough audio stream state machine is described below : > > + > > + +----------+ > > + | | > > + | OPEN | > > + | | > > + +----------+ > > + | > > + | > > + | compr_set_params() > > + | > > + v > > + all passthrough task ops +----------+ > > + +------------------------------------| | > > + | | SETUP | > > + | | > > + | +----------+ > > + | | > > + +------------------------------------------+ > > + > > + > > +Passthrough operations (ioctls) > > +=============================== > > + > > +CREATE > > +------ > > +Creates a set of input/output buffers. The input buffer size is > > +fragment_size. Allocates unique seqno. > > + > > +The hardware drivers allocate internal 'struct dma_buf' for both input and > > +output buffers (using 'dma_buf_export()' function). The anonymous > > +file descriptors for those buffers are passed to user space. > > + > > Audio data is always separated into a lot of periods. so does this mean > that the call sequence is "CREATE" (user fill period data to buffer ) "START" > -> "CREATE" (user fill period data to buffer )"START" > -> "CREATE" (user fill period data to buffer )"START".... ? > > Will this cause memory fragmentation? > > How can the user get each output? > Or does this mean the sequence should be: > "CREATE" > (user space fill period data to buffer ) > "START" > "STOP" : if the task is running, stop it there is no output generated? > "STATUS": polling the status to check the task finished for every task? > then another loop for each period? > Per my understanding, I use the below sequence: create -> (start, stop, status) -> (start, stop, status) ...-> free. Below are issues found in the code. diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c index da048e61c574..7b6168d43d41 100644 --- a/sound/core/compress_offload.c +++ b/sound/core/compress_offload.c @@ -134,6 +134,7 @@ static int snd_compr_open(struct inode *inode, struct file *f) } runtime->state = SNDRV_PCM_STATE_OPEN; init_waitqueue_head(&runtime->sleep); + INIT_LIST_HEAD(&runtime->tasks); data->stream.runtime = runtime; f->private_data = (void *)data; scoped_guard(mutex, &compr->lock) @@ -1003,10 +1004,6 @@ static struct snd_compr_task_runtime * static void snd_compr_task_free(struct snd_compr_task_runtime *task) { - if (task->output) - dma_buf_put(task->output); - if (task->input) - dma_buf_put(task->input); kfree(task); } @@ -1045,6 +1042,7 @@ static int snd_compr_task_new(struct snd_compr_stream *stream, struct snd_compr_ retval = utask->output_fd; goto cleanup; } + utask->seqno = task->seqno; list_add_tail(&task->list, &stream->runtime->tasks); stream->runtime->total_tasks++; return 0; There is no dma_buf_get() called, so remove the dma_buf_put(). Best regards Shengjiu Wang > > > +FREE > > +---- > > +Free a set of input/output buffers. If a task is active, the stop > > +operation is executed before. If seqno is zero, operation is executed for all > > +tasks. > > + > > +START > > +----- > > +Starts (queues) a task. There are two cases of the task start - right after > > +the task is created. In this case, origin_seqno must be zero. > > +The second case is for reusing of already finished task. The origin_seqno > > +must identify the task to be reused. In both cases, a new seqno value > > +is allocated and returned to user space. > > + > > +The prerequisite is that application filled input dma buffer with > > +new source data and set input_size to pass the real data size to the driver. > > + > > +The order of data processing is preserved (first started job must be > > +finished at first). > > + > > +STOP > > +---- > > +Stop (dequeues) a task. If seqno is zero, operation is executed for all > > +tasks. > > + > > +STATUS > > +------ > > +Obtain the task status (active, finished). Also, the driver will set > > +the real output data size (valid area in the output buffer). > > + > > +Credits > > +======= > > +- ... > > diff --git a/include/sound/compress_driver.h b/include/sound/compress_driver.h > > index bcf872c17dd3..2884b1e7955d 100644 > > --- a/include/sound/compress_driver.h > > +++ b/include/sound/compress_driver.h > > @@ -19,6 +19,22 @@ > > > > struct snd_compr_ops; > > > > +/** > > + * struct snd_compr_task_runtime: task runtime description > > + * > > + */ > > +struct snd_compr_task_runtime { > > + struct list_head list; > > + struct dma_buf *input; > > + struct dma_buf *output; > > + u64 seqno; > > + u64 input_size; > > + u64 output_size; > > + u8 state; > > + void *private_value; > > +}; > > + > > + > > /** > > * struct snd_compr_runtime: runtime stream description > > * @state: stream state > > @@ -54,6 +70,11 @@ struct snd_compr_runtime { > > dma_addr_t dma_addr; > > size_t dma_bytes; > > struct snd_dma_buffer *dma_buffer_p; > > + > > + u32 active_tasks; > > + u32 total_tasks; > > + u64 task_seqno; > > + struct list_head tasks; > > }; > > > > /** > > @@ -132,6 +153,12 @@ struct snd_compr_ops { > > struct snd_compr_caps *caps); > > int (*get_codec_caps) (struct snd_compr_stream *stream, > > struct snd_compr_codec_caps *codec); > > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > > + int (*task_create) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); > > + int (*task_start) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); > > + int (*task_stop) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); > > + int (*task_free) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); > > +#endif > > }; > > > > /** > > @@ -242,4 +269,9 @@ int snd_compr_free_pages(struct snd_compr_stream *stream); > > int snd_compr_stop_error(struct snd_compr_stream *stream, > > snd_pcm_state_t state); > > > > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > > +void snd_compr_task_finished(struct snd_compr_stream *stream, > > + struct snd_compr_task_runtime *task); > > +#endif > > + > > #endif > > diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h > > index d185957f3fe0..5fed1979522b 100644 > > --- a/include/uapi/sound/compress_offload.h > > +++ b/include/uapi/sound/compress_offload.h > > @@ -1,4 +1,4 @@ > > -/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > > + /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > > /* > > * compress_offload.h - compress offload header definations > > * > > @@ -14,7 +14,7 @@ > > #include <sound/compress_params.h> > > > > > > -#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 2, 0) > > +#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 3, 0) > > /** > > * struct snd_compressed_buffer - compressed buffer > > * @fragment_size: size of buffer fragment in bytes > > @@ -68,7 +68,8 @@ struct snd_compr_avail { > > > > enum snd_compr_direction { > > SND_COMPRESS_PLAYBACK = 0, > > - SND_COMPRESS_CAPTURE > > + SND_COMPRESS_CAPTURE, > > + SND_COMPRESS_PASSTHROUGH > > }; > > > > /** > > @@ -127,6 +128,42 @@ struct snd_compr_metadata { > > __u32 value[8]; > > } __attribute__((packed, aligned(4))); > > > > +/** > > + * struct snd_compr_task - task primitive for non-realtime operation > > + * @seqno: sequence number (task identifier) > > + * @origin_seqno: previous sequence number (task identifier) - for reuse > > + * @input_fd: data input file descriptor (dma-buf) > > + * @output_fd: data output file descriptor (dma-buf) > > + * @input_size: filled data in bytes (from caller, must not exceed fragment size) > > + */ > > +struct snd_compr_task { > > + __u64 seqno; > > + __u64 origin_seqno; > > + int input_fd; > > + int output_fd; > > + __u64 input_size; > > + __u8 reserved[16]; > > +} __attribute__((packed, aligned(4))); > > + > > +enum snd_compr_state { > > + SND_COMPRESS_TASK_STATE_IDLE = 0, > > + SND_COMPRESS_TASK_STATE_ACTIVE, > > + SND_COMPRESS_TASK_STATE_FINISHED > > +}; > > + > > +/** > > + * struct snd_compr_task_status - task status > > + * @seqno: sequence number (task identifier) > > + * @output_size: filled data in bytes (from driver) > > + * @state: actual task state (SND_COMPRESS_TASK_STATE_*) > > + */ > > +struct snd_compr_task_status { > > + __u64 seqno; > > + __u64 output_size; > > + __u8 state; > > + __u8 reserved[15]; > > +} __attribute__((packed, aligned(4))); > > + > > /* > > * compress path ioctl definitions > > * SNDRV_COMPRESS_GET_CAPS: Query capability of DSP > > @@ -164,6 +201,14 @@ struct snd_compr_metadata { > > #define SNDRV_COMPRESS_DRAIN _IO('C', 0x34) > > #define SNDRV_COMPRESS_NEXT_TRACK _IO('C', 0x35) > > #define SNDRV_COMPRESS_PARTIAL_DRAIN _IO('C', 0x36) > > + > > + > > +#define SNDRV_COMPRESS_TASK_CREATE _IOWR('C', 0x60, struct snd_compr_task) > > +#define SNDRV_COMPRESS_TASK_FREE _IOW('C', 0x61, __u64) > > +#define SNDRV_COMPRESS_TASK_START _IOWR('C', 0x62, struct snd_compr_task) > > +#define SNDRV_COMPRESS_TASK_STOP _IOW('C', 0x63, __u64) > > +#define SNDRV_COMPRESS_TASK_STATUS _IOWR('C', 0x68, struct snd_compr_task_status) > > + > > /* > > * TODO > > * 1. add mmap support > > diff --git a/sound/core/Kconfig b/sound/core/Kconfig > > index 8077f481d84f..3541fe6d477f 100644 > > --- a/sound/core/Kconfig > > +++ b/sound/core/Kconfig > > @@ -59,6 +59,10 @@ config SND_CORE_TEST > > config SND_COMPRESS_OFFLOAD > > tristate > > > > +config SND_COMPRESS_PASSTHROUGH > > + select DMA_BUF > > + tristate > > + > > config SND_JACK > > bool > > > > diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c > > index f0008fa2d839..da048e61c574 100644 > > --- a/sound/core/compress_offload.c > > +++ b/sound/core/compress_offload.c > > @@ -24,6 +24,7 @@ > > #include <linux/types.h> > > #include <linux/uio.h> > > #include <linux/uaccess.h> > > +#include <linux/dma-buf.h> > > #include <linux/module.h> > > #include <linux/compat.h> > > #include <sound/core.h> > > @@ -54,6 +55,12 @@ struct snd_compr_file { > > > > static void error_delayed_work(struct work_struct *work); > > > > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > > +static void snd_compr_task_free_all(struct snd_compr_stream *stream); > > +#else > > +static inline void snd_compr_task_free_all(struct snd_compr_stream *stream) { } > > +#endif > > + > > /* > > * a note on stream states used: > > * we use following states in the compressed core > > @@ -85,6 +92,8 @@ static int snd_compr_open(struct inode *inode, struct file *f) > > dirn = SND_COMPRESS_PLAYBACK; > > else if ((f->f_flags & O_ACCMODE) == O_RDONLY) > > dirn = SND_COMPRESS_CAPTURE; > > + else if ((f->f_flags & O_ACCMODE) == O_RDWR) > > + dirn = SND_COMPRESS_PASSTHROUGH; > > else > > return -EINVAL; > > > > @@ -154,6 +163,8 @@ static int snd_compr_free(struct inode *inode, struct file *f) > > break; > > } > > > > + snd_compr_task_free_all(&data->stream); > > + > > data->stream.ops->free(&data->stream); > > if (!data->stream.runtime->dma_buffer_p) > > kfree(data->stream.runtime->buffer); > > @@ -226,6 +237,9 @@ snd_compr_ioctl_avail(struct snd_compr_stream *stream, unsigned long arg) > > struct snd_compr_avail ioctl_avail; > > size_t avail; > > > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > > + return -EBADFD; > > + > > avail = snd_compr_calc_avail(stream, &ioctl_avail); > > ioctl_avail.avail = avail; > > > > @@ -287,6 +301,8 @@ static ssize_t snd_compr_write(struct file *f, const char __user *buf, > > return -EFAULT; > > > > stream = &data->stream; > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > > + return -EBADFD; > > guard(mutex)(&stream->device->lock); > > /* write is allowed when stream is running or has been steup */ > > switch (stream->runtime->state) { > > @@ -336,6 +352,8 @@ static ssize_t snd_compr_read(struct file *f, char __user *buf, > > return -EFAULT; > > > > stream = &data->stream; > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > > + return -EBADFD; > > guard(mutex)(&stream->device->lock); > > > > /* read is allowed when stream is running, paused, draining and setup > > @@ -385,6 +403,8 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) > > { > > struct snd_compr_file *data = f->private_data; > > struct snd_compr_stream *stream; > > + struct snd_compr_runtime *runtime; > > + struct snd_compr_task_runtime *task; > > size_t avail; > > __poll_t retval = 0; > > > > @@ -392,6 +412,7 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) > > return EPOLLERR; > > > > stream = &data->stream; > > + runtime = stream->runtime; > > > > guard(mutex)(&stream->device->lock); > > > > @@ -405,6 +426,18 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) > > > > poll_wait(f, &stream->runtime->sleep, wait); > > > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) { > > + if (runtime->fragments > runtime->active_tasks) > > + retval |= EPOLLOUT | EPOLLWRNORM; > > + task = list_first_entry_or_null(&runtime->tasks, > > + struct snd_compr_task_runtime, > > + list); > > + if (task && task->state == SND_COMPRESS_TASK_STATE_FINISHED) > > + retval |= EPOLLIN | EPOLLRDNORM; > > + return retval; > > + } > > + > > + > > avail = snd_compr_get_avail(stream); > > pr_debug("avail is %ld\n", (unsigned long)avail); > > /* check if we have at least one fragment to fill */ > > @@ -521,6 +554,9 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream, > > unsigned int buffer_size; > > void *buffer = NULL; > > > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > > + goto params; > > + > > buffer_size = params->buffer.fragment_size * params->buffer.fragments; > > if (stream->ops->copy) { > > buffer = NULL; > > @@ -543,18 +579,30 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream, > > if (!buffer) > > return -ENOMEM; > > } > > - stream->runtime->fragment_size = params->buffer.fragment_size; > > - stream->runtime->fragments = params->buffer.fragments; > > + > > stream->runtime->buffer = buffer; > > stream->runtime->buffer_size = buffer_size; > > +params: > > + stream->runtime->fragment_size = params->buffer.fragment_size; > > + stream->runtime->fragments = params->buffer.fragments; > > return 0; > > } > > > > -static int snd_compress_check_input(struct snd_compr_params *params) > > +static int > > +snd_compress_check_input(struct snd_compr_stream *stream, struct snd_compr_params *params) > > { > > + u32 max_fragments; > > + > > /* first let's check the buffer parameter's */ > > - if (params->buffer.fragment_size == 0 || > > - params->buffer.fragments > U32_MAX / params->buffer.fragment_size || > > + if (params->buffer.fragment_size == 0) > > + return -EINVAL; > > + > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) > > + max_fragments = 64; /* safe value */ > > + else > > + max_fragments = U32_MAX / params->buffer.fragment_size; > > + > > + if (params->buffer.fragments > max_fragments || > > params->buffer.fragments == 0) > > return -EINVAL; > > > > @@ -583,7 +631,7 @@ snd_compr_set_params(struct snd_compr_stream *stream, unsigned long arg) > > if (IS_ERR(params)) > > return PTR_ERR(no_free_ptr(params)); > > > > - retval = snd_compress_check_input(params); > > + retval = snd_compress_check_input(stream, params); > > if (retval) > > return retval; > > > > @@ -939,6 +987,259 @@ static int snd_compr_partial_drain(struct snd_compr_stream *stream) > > return snd_compress_wait_for_drain(stream); > > } > > > > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > > + > > +static struct snd_compr_task_runtime * > > + snd_compr_find_task(struct snd_compr_stream *stream, __u64 seqno) > > +{ > > + struct snd_compr_task_runtime *task; > > + > > + list_for_each_entry(task, &stream->runtime->tasks, list) { > > + if (task->seqno == seqno) > > + return task; > > + } > > + return NULL; > > +} > > + > > +static void snd_compr_task_free(struct snd_compr_task_runtime *task) > > +{ > > + if (task->output) > > + dma_buf_put(task->output); > > + if (task->input) > > + dma_buf_put(task->input); > > + kfree(task); > > +} > > + > > +static u64 snd_compr_seqno_next(struct snd_compr_stream *stream) > > +{ > > + u64 seqno = ++stream->runtime->task_seqno; > > + if (seqno == 0) > > + seqno = ++stream->runtime->task_seqno; > > + return seqno; > > +} > > + > > +static int snd_compr_task_new(struct snd_compr_stream *stream, struct snd_compr_task *utask) > > +{ > > + struct snd_compr_task_runtime *task; > > + int retval; > > + > > + if (stream->runtime->total_tasks >= stream->runtime->fragments) > > + return -EBUSY; > > + if (utask->origin_seqno != 0 || utask->input_size != 0) > > + return -EINVAL; > > + task = kzalloc(sizeof(*task), GFP_KERNEL); > > + if (task == NULL) > > + return -ENOMEM; > > + task->seqno = snd_compr_seqno_next(stream); > > + task->input_size = utask->input_size; > > + retval = stream->ops->task_create(stream, task); > > + if (retval < 0) > > + goto cleanup; > > + utask->input_fd = dma_buf_fd(task->input, O_WRONLY|O_CLOEXEC); > > + if (utask->input_fd < 0) { > > + retval = utask->input_fd; > > + goto cleanup; > > + } > > + utask->output_fd = dma_buf_fd(task->output, O_RDONLY|O_CLOEXEC); > > + if (utask->output_fd < 0) { > > + retval = utask->output_fd; > > + goto cleanup; > > + } > > + list_add_tail(&task->list, &stream->runtime->tasks); > > + stream->runtime->total_tasks++; > > + return 0; > > +cleanup: > > + snd_compr_task_free(task); > > + return retval; > > +} > > + > > +static int snd_compr_task_create(struct snd_compr_stream *stream, unsigned long arg) > > +{ > > + struct snd_compr_task *task __free(kfree) = NULL; > > + int retval; > > + > > + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) > > + return -EPERM; > > + task = memdup_user((void __user *)arg, sizeof(*task)); > > + if (IS_ERR(task)) > > + return PTR_ERR(no_free_ptr(task)); > > + retval = snd_compr_task_new(stream, task); > > + if (retval >= 0) > > + if (copy_to_user((void __user *)arg, task, sizeof(*task))) > > + retval = -EFAULT; > > + return retval; > > +} > > + > > +static int snd_compr_task_start_prepare(struct snd_compr_task_runtime *task, > > + struct snd_compr_task *utask) > > +{ > > + if (task == NULL) > > + return -EINVAL; > > + if (task->state >= SND_COMPRESS_TASK_STATE_FINISHED) > > + return -EBUSY; > > + if (utask->input_size > task->input->size) > > + return -EINVAL; > > + task->input_size = utask->input_size; > > + task->state = SND_COMPRESS_TASK_STATE_IDLE; > > + return 0; > > +} > > + > > +static int snd_compr_task_start(struct snd_compr_stream *stream, struct snd_compr_task *utask) > > +{ > > + struct snd_compr_task_runtime *task; > > + int retval; > > + > > + if (utask->origin_seqno > 0) { > > + task = snd_compr_find_task(stream, utask->seqno); > > + retval = snd_compr_task_start_prepare(task, utask); > > + if (retval < 0) > > + return retval; > > + task->seqno = utask->seqno = snd_compr_seqno_next(stream); > > + utask->origin_seqno = 0; > > + list_move_tail(&task->list, &stream->runtime->tasks); > > + } else { > > + task = snd_compr_find_task(stream, utask->seqno); > > + if (task && task->state != SND_COMPRESS_TASK_STATE_IDLE) > > + return -EBUSY; > > + retval = snd_compr_task_start_prepare(task, utask); > > + if (retval < 0) > > + return retval; > > + } > > + retval = stream->ops->task_start(stream, task); > > + if (retval >= 0) { > > + task->state = SND_COMPRESS_TASK_STATE_ACTIVE; > > + stream->runtime->active_tasks++; > > + } > > + return retval; > > +} > > + > > +static int snd_compr_task_start_ioctl(struct snd_compr_stream *stream, unsigned long arg) > > +{ > > + struct snd_compr_task *task __free(kfree) = NULL; > > + int retval; > > + > > + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) > > + return -EPERM; > > + task = memdup_user((void __user *)arg, sizeof(*task)); > > + if (IS_ERR(task)) > > + return PTR_ERR(no_free_ptr(task)); > > + retval = snd_compr_task_start(stream, task); > > + if (retval >= 0) > > + if (copy_to_user((void __user *)arg, task, sizeof(*task))) > > + retval = -EFAULT; > > + return retval; > > +} > > + > > +static void snd_compr_task_stop_one(struct snd_compr_stream *stream, > > + struct snd_compr_task_runtime *task) > > +{ > > + if (task->state != SND_COMPRESS_TASK_STATE_ACTIVE) > > + return; > > + stream->ops->task_stop(stream, task); > > + if (!snd_BUG_ON(stream->runtime->active_tasks == 0)) > > + stream->runtime->active_tasks--; > > + list_move_tail(&task->list, &stream->runtime->tasks); > > + task->state = SND_COMPRESS_TASK_STATE_IDLE; > > +} > > + > > +static void snd_compr_task_free_one(struct snd_compr_stream *stream, > > + struct snd_compr_task_runtime *task) > > +{ > > + snd_compr_task_stop_one(stream, task); > > + stream->ops->task_free(stream, task); > > + list_del(&task->list); > > + snd_compr_task_free(task); > > + stream->runtime->total_tasks--; > > +} > > + > > +static void snd_compr_task_free_all(struct snd_compr_stream *stream) > > +{ > > + struct snd_compr_task_runtime *task; > > + > > + list_for_each_entry(task, &stream->runtime->tasks, list) > > + snd_compr_task_free_one(stream, task); > > +} > > + > > +typedef void (*snd_compr_seq_func_t)(struct snd_compr_stream *stream, > > + struct snd_compr_task_runtime *task); > > + > > +static int snd_compr_task_seq(struct snd_compr_stream *stream, unsigned long arg, > > + snd_compr_seq_func_t fcn) > > +{ > > + struct snd_compr_task_runtime *task; > > + __u64 seqno; > > + int retval; > > + > > + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) > > + return -EPERM; > > + retval = get_user(seqno, (__u64 __user *)arg); > > + if (retval < 0) > > + return retval; > > + retval = 0; > > + if (seqno == 0) { > > + list_for_each_entry(task, &stream->runtime->tasks, list) > > + fcn(stream, task); > > + } else { > > + task = snd_compr_find_task(stream, seqno); > > + if (task == NULL) { > > + retval = -EINVAL; > > + } else { > > + fcn(stream, task); > > + } > > + } > > + return retval; > > +} > > + > > +static int snd_compr_task_status(struct snd_compr_stream *stream, > > + struct snd_compr_task_status *status) > > +{ > > + struct snd_compr_task_runtime *task; > > + > > + task = snd_compr_find_task(stream, status->seqno); > > + if (task == NULL) > > + return -EINVAL; > > + status->output_size = task->output_size; > > + status->state = task->state; > > + return 0; > > +} > > + > > +static int snd_compr_task_status_ioctl(struct snd_compr_stream *stream, unsigned long arg) > > +{ > > + struct snd_compr_task_status *status __free(kfree) = NULL; > > + int retval; > > + > > + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) > > + return -EPERM; > > + status = memdup_user((void __user *)arg, sizeof(*status)); > > + if (IS_ERR(status)) > > + return PTR_ERR(no_free_ptr(status)); > > + retval = snd_compr_task_status(stream, status); > > + if (retval >= 0) > > + if (copy_to_user((void __user *)arg, status, sizeof(*status))) > > + retval = -EFAULT; > > + return retval; > > +} > > + > > +/** > > + * snd_compr_task_finished: Notify that the task was finished > > + * @stream: pointer to stream > > + * @task: runtime task structure > > + * > > + * Set the finished task state and notify waiters. > > + */ > > +void snd_compr_task_finished(struct snd_compr_stream *stream, > > + struct snd_compr_task_runtime *task) > > +{ > > + guard(mutex)(&stream->device->lock); > > + if (!snd_BUG_ON(stream->runtime->active_tasks == 0)) > > + stream->runtime->active_tasks--; > > + task->state = SND_COMPRESS_TASK_STATE_FINISHED; > > + wake_up(&stream->runtime->sleep); > > +} > > +EXPORT_SYMBOL(snd_compr_task_finished); > > + > > +#endif /* CONFIG_COMPRESS_PASSTHROUGH */ > > + > > static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg) > > { > > struct snd_compr_file *data = f->private_data; > > @@ -968,6 +1269,27 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg) > > return snd_compr_set_metadata(stream, arg); > > case _IOC_NR(SNDRV_COMPRESS_GET_METADATA): > > return snd_compr_get_metadata(stream, arg); > > + } > > + > > + if (stream->direction == SND_COMPRESS_PASSTHROUGH) { > > +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) > > + switch (_IOC_NR(cmd)) { > > + case _IOC_NR(SNDRV_COMPRESS_TASK_CREATE): > > + return snd_compr_task_create(stream, arg); > > + case _IOC_NR(SNDRV_COMPRESS_TASK_FREE): > > + return snd_compr_task_seq(stream, arg, snd_compr_task_free_one); > > + case _IOC_NR(SNDRV_COMPRESS_TASK_START): > > + return snd_compr_task_start_ioctl(stream, arg); > > + case _IOC_NR(SNDRV_COMPRESS_TASK_STOP): > > + return snd_compr_task_seq(stream, arg, snd_compr_task_stop_one); > > + case _IOC_NR(SNDRV_COMPRESS_TASK_STATUS): > > + return snd_compr_task_status_ioctl(stream, arg); > > + } > > +#endif > > + return -ENOTTY; > > + } > > + > > + switch (_IOC_NR(cmd)) { > > case _IOC_NR(SNDRV_COMPRESS_TSTAMP): > > return snd_compr_tstamp(stream, arg); > > case _IOC_NR(SNDRV_COMPRESS_AVAIL): > > -- > > 2.45.1 > >
On 03. 06. 24 10:31, Shengjiu Wang wrote: > On Tue, May 28, 2024 at 7:14 PM Shengjiu Wang <shengjiu.wang@gmail.com> wrote: >> >> On Mon, May 27, 2024 at 8:23 PM Jaroslav Kysela <perex@perex.cz> wrote: >>> >>> There is a requirement to expose the audio hardware that accelerates various >>> tasks for user space such as sample rate converters, compressed >>> stream decoders, etc. >>> >>> This is description for the API extension for the compress ALSA API which >>> is able to handle "tasks" that are not bound to real-time operations >>> and allows for the serialization of operations. >>> >>> For details, refer to "compress-passthrough.rst" document. >>> >>> Note: This code is RFC (not tested, just to clearify the API requirements). >>> My goal is to add a test (loopback) driver and add a support to tinycompress >>> library in the next step. >>> >>> Cc: Mark Brown <broonie@kernel.org> >>> Cc: Shengjiu Wang <shengjiu.wang@gmail.com> >>> Cc: Nicolas Dufresne <nicolas@ndufresne.ca> >>> Cc: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com> >>> Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> >>> Cc: Vinod Koul <vkoul@kernel.org> >>> Signed-off-by: Jaroslav Kysela <perex@perex.cz> >>> >>> --- >>> v1..v2: >>> - fix some documentation typos (thanks Amadeusz Sławiński) >>> - fix memdup_user() error handling (thanks Takashi) >>> - use one state variable instead multiple (thanks Takashi) >>> - handle task limit (set to 64 - mentioned in documentation, NIY) >>> - fix file release (free all tasks) >>> --- >>> .../sound/designs/compress-passthrough.rst | 125 +++++++ >>> include/sound/compress_driver.h | 32 ++ >>> include/uapi/sound/compress_offload.h | 51 ++- >>> sound/core/Kconfig | 4 + >>> sound/core/compress_offload.c | 334 +++++++++++++++++- >>> 5 files changed, 537 insertions(+), 9 deletions(-) >>> create mode 100644 Documentation/sound/designs/compress-passthrough.rst >>> >>> diff --git a/Documentation/sound/designs/compress-passthrough.rst b/Documentation/sound/designs/compress-passthrough.rst >>> new file mode 100644 >>> index 000000000000..975462500c33 >>> --- /dev/null >>> +++ b/Documentation/sound/designs/compress-passthrough.rst >>> @@ -0,0 +1,125 @@ >>> +================================= >>> +ALSA Co-processor Passthrough API >>> +================================= >>> + >>> +Jaroslav Kysela <perex@perex.cz> >>> + >>> + >>> +Overview >>> +======== >>> + >>> +There is a requirement to expose the audio hardware that accelerates various >>> +tasks for user space such as sample rate converters, compressed >>> +stream decoders, etc. >>> + >>> +This is description for the API extension for the compress ALSA API which >>> +is able to handle "tasks" that are not bound to real-time operations >>> +and allows for the serialization of operations. >>> + >>> +Requirements >>> +============ >>> + >>> +The main requirements are: >>> + >>> +- serialization of multiple tasks for user space to allow multiple >>> + operations without user space intervention >>> + >>> +- separate buffers (input + output) for each operation >>> + >>> +- expose buffers using mmap to user space >>> + >>> +- signal user space when the task is finished (standard poll mechanism) >>> + >>> +Design >>> +====== >>> + >>> +A new direction SND_COMPRESS_PASSTHROUGH is introduced to identify >>> +the passthrough API. >>> + >>> +The API extension shares device enumeration and parameters handling from >>> +the main compressed API. All other realtime streaming ioctls are deactivated >>> +and a new set of task related ioctls are introduced. The standard >>> +read/write/mmap I/O operations are not supported in the passthrough device. >>> + >>> +Device ("stream") state handling is reduced to OPEN/SETUP. All other >>> +states are not available for the passthrough mode. >>> + >>> +Data I/O mechanism is using standard dma-buf interface with all advantages >>> +like mmap, standard I/O, buffer sharing etc. One buffer is used for the >>> +input data and second (separate) buffer is used for the output data. Each task >>> +have separate I/O buffers. >>> + >>> +For the buffering parameters, the fragments means a limit of allocated tasks >>> +for given device. The fragment_size limits the input buffer size for the given >>> +device. The output buffer size is determined by the driver (may be different >>> +from the input buffer size). >>> + >>> +State Machine >>> +============= >>> + >>> +The passthrough audio stream state machine is described below : >>> + >>> + +----------+ >>> + | | >>> + | OPEN | >>> + | | >>> + +----------+ >>> + | >>> + | >>> + | compr_set_params() >>> + | >>> + v >>> + all passthrough task ops +----------+ >>> + +------------------------------------| | >>> + | | SETUP | >>> + | | >>> + | +----------+ >>> + | | >>> + +------------------------------------------+ >>> + >>> + >>> +Passthrough operations (ioctls) >>> +=============================== >>> + >>> +CREATE >>> +------ >>> +Creates a set of input/output buffers. The input buffer size is >>> +fragment_size. Allocates unique seqno. >>> + >>> +The hardware drivers allocate internal 'struct dma_buf' for both input and >>> +output buffers (using 'dma_buf_export()' function). The anonymous >>> +file descriptors for those buffers are passed to user space. >>> + >> >> Audio data is always separated into a lot of periods. so does this mean >> that the call sequence is "CREATE" (user fill period data to buffer ) "START" >> -> "CREATE" (user fill period data to buffer )"START" >> -> "CREATE" (user fill period data to buffer )"START".... ? >> >> Will this cause memory fragmentation? >> >> How can the user get each output? >> Or does this mean the sequence should be: >> "CREATE" >> (user space fill period data to buffer ) >> "START" >> "STOP" : if the task is running, stop it there is no output generated? >> "STATUS": polling the status to check the task finished for every task? >> then another loop for each period? >> > > Per my understanding, I use the below sequence: > create -> (start, stop, status) -> (start, stop, status) ...-> free. The stop is optional. When the driver calls snd_compr_task_finished(), it's expected that the task has finished (stopped) and the next started task in the queue is processed. > Below are issues found in the code. > diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c > index da048e61c574..7b6168d43d41 100644 > --- a/sound/core/compress_offload.c > +++ b/sound/core/compress_offload.c > @@ -134,6 +134,7 @@ static int snd_compr_open(struct inode *inode, > struct file *f) > } > runtime->state = SNDRV_PCM_STATE_OPEN; > init_waitqueue_head(&runtime->sleep); > + INIT_LIST_HEAD(&runtime->tasks); Thanks. > data->stream.runtime = runtime; > f->private_data = (void *)data; > scoped_guard(mutex, &compr->lock) > @@ -1003,10 +1004,6 @@ static struct snd_compr_task_runtime * > > static void snd_compr_task_free(struct snd_compr_task_runtime *task) > { > - if (task->output) > - dma_buf_put(task->output); > - if (task->input) > - dma_buf_put(task->input); > kfree(task); > } See bellow. > @@ -1045,6 +1042,7 @@ static int snd_compr_task_new(struct > snd_compr_stream *stream, struct snd_compr_ > retval = utask->output_fd; > goto cleanup; > } > + utask->seqno = task->seqno; Thanks. > list_add_tail(&task->list, &stream->runtime->tasks); > stream->runtime->total_tasks++; > return 0; > > There is no dma_buf_get() called, so remove the dma_buf_put(). I expected that the driver will increase this reference counter in the task_create callback. But yes, it will be probably better to do in snd_compr_task_new() when file descriptors are used. I will send v3 soon. Thank you for your comments. Jaroslav
On Mon, Jun 3, 2024 at 4:57 PM Jaroslav Kysela <perex@perex.cz> wrote: > > On 03. 06. 24 10:31, Shengjiu Wang wrote: > > On Tue, May 28, 2024 at 7:14 PM Shengjiu Wang <shengjiu.wang@gmail.com> wrote: > >> > >> On Mon, May 27, 2024 at 8:23 PM Jaroslav Kysela <perex@perex.cz> wrote: > >>> > >>> There is a requirement to expose the audio hardware that accelerates various > >>> tasks for user space such as sample rate converters, compressed > >>> stream decoders, etc. > >>> > >>> This is description for the API extension for the compress ALSA API which > >>> is able to handle "tasks" that are not bound to real-time operations > >>> and allows for the serialization of operations. > >>> > >>> For details, refer to "compress-passthrough.rst" document. > >>> > >>> Note: This code is RFC (not tested, just to clearify the API requirements). > >>> My goal is to add a test (loopback) driver and add a support to tinycompress > >>> library in the next step. > >>> > >>> Cc: Mark Brown <broonie@kernel.org> > >>> Cc: Shengjiu Wang <shengjiu.wang@gmail.com> > >>> Cc: Nicolas Dufresne <nicolas@ndufresne.ca> > >>> Cc: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com> > >>> Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> > >>> Cc: Vinod Koul <vkoul@kernel.org> > >>> Signed-off-by: Jaroslav Kysela <perex@perex.cz> > >>> > >>> --- > >>> v1..v2: > >>> - fix some documentation typos (thanks Amadeusz Sławiński) > >>> - fix memdup_user() error handling (thanks Takashi) > >>> - use one state variable instead multiple (thanks Takashi) > >>> - handle task limit (set to 64 - mentioned in documentation, NIY) > >>> - fix file release (free all tasks) > >>> --- > >>> .../sound/designs/compress-passthrough.rst | 125 +++++++ > >>> include/sound/compress_driver.h | 32 ++ > >>> include/uapi/sound/compress_offload.h | 51 ++- > >>> sound/core/Kconfig | 4 + > >>> sound/core/compress_offload.c | 334 +++++++++++++++++- > >>> 5 files changed, 537 insertions(+), 9 deletions(-) > >>> create mode 100644 Documentation/sound/designs/compress-passthrough.rst > >>> > >>> diff --git a/Documentation/sound/designs/compress-passthrough.rst b/Documentation/sound/designs/compress-passthrough.rst > >>> new file mode 100644 > >>> index 000000000000..975462500c33 > >>> --- /dev/null > >>> +++ b/Documentation/sound/designs/compress-passthrough.rst > >>> @@ -0,0 +1,125 @@ > >>> +================================= > >>> +ALSA Co-processor Passthrough API > >>> +================================= > >>> + > >>> +Jaroslav Kysela <perex@perex.cz> > >>> + > >>> + > >>> +Overview > >>> +======== > >>> + > >>> +There is a requirement to expose the audio hardware that accelerates various > >>> +tasks for user space such as sample rate converters, compressed > >>> +stream decoders, etc. > >>> + > >>> +This is description for the API extension for the compress ALSA API which > >>> +is able to handle "tasks" that are not bound to real-time operations > >>> +and allows for the serialization of operations. > >>> + > >>> +Requirements > >>> +============ > >>> + > >>> +The main requirements are: > >>> + > >>> +- serialization of multiple tasks for user space to allow multiple > >>> + operations without user space intervention > >>> + > >>> +- separate buffers (input + output) for each operation > >>> + > >>> +- expose buffers using mmap to user space > >>> + > >>> +- signal user space when the task is finished (standard poll mechanism) > >>> + > >>> +Design > >>> +====== > >>> + > >>> +A new direction SND_COMPRESS_PASSTHROUGH is introduced to identify > >>> +the passthrough API. > >>> + > >>> +The API extension shares device enumeration and parameters handling from > >>> +the main compressed API. All other realtime streaming ioctls are deactivated > >>> +and a new set of task related ioctls are introduced. The standard > >>> +read/write/mmap I/O operations are not supported in the passthrough device. > >>> + > >>> +Device ("stream") state handling is reduced to OPEN/SETUP. All other > >>> +states are not available for the passthrough mode. > >>> + > >>> +Data I/O mechanism is using standard dma-buf interface with all advantages > >>> +like mmap, standard I/O, buffer sharing etc. One buffer is used for the > >>> +input data and second (separate) buffer is used for the output data. Each task > >>> +have separate I/O buffers. > >>> + > >>> +For the buffering parameters, the fragments means a limit of allocated tasks > >>> +for given device. The fragment_size limits the input buffer size for the given > >>> +device. The output buffer size is determined by the driver (may be different > >>> +from the input buffer size). > >>> + > >>> +State Machine > >>> +============= > >>> + > >>> +The passthrough audio stream state machine is described below : > >>> + > >>> + +----------+ > >>> + | | > >>> + | OPEN | > >>> + | | > >>> + +----------+ > >>> + | > >>> + | > >>> + | compr_set_params() > >>> + | > >>> + v > >>> + all passthrough task ops +----------+ > >>> + +------------------------------------| | > >>> + | | SETUP | > >>> + | | > >>> + | +----------+ > >>> + | | > >>> + +------------------------------------------+ > >>> + > >>> + > >>> +Passthrough operations (ioctls) > >>> +=============================== > >>> + > >>> +CREATE > >>> +------ > >>> +Creates a set of input/output buffers. The input buffer size is > >>> +fragment_size. Allocates unique seqno. > >>> + > >>> +The hardware drivers allocate internal 'struct dma_buf' for both input and > >>> +output buffers (using 'dma_buf_export()' function). The anonymous > >>> +file descriptors for those buffers are passed to user space. > >>> + > >> > >> Audio data is always separated into a lot of periods. so does this mean > >> that the call sequence is "CREATE" (user fill period data to buffer ) "START" > >> -> "CREATE" (user fill period data to buffer )"START" > >> -> "CREATE" (user fill period data to buffer )"START".... ? > >> > >> Will this cause memory fragmentation? > >> > >> How can the user get each output? > >> Or does this mean the sequence should be: > >> "CREATE" > >> (user space fill period data to buffer ) > >> "START" > >> "STOP" : if the task is running, stop it there is no output generated? > >> "STATUS": polling the status to check the task finished for every task? > >> then another loop for each period? > >> > > > > Per my understanding, I use the below sequence: > > create -> (start, stop, status) -> (start, stop, status) ...-> free. > > The stop is optional. When the driver calls snd_compr_task_finished(), it's > expected that the task has finished (stopped) and the next started task in the > queue is processed. > > > Below are issues found in the code. > > diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c > > index da048e61c574..7b6168d43d41 100644 > > --- a/sound/core/compress_offload.c > > +++ b/sound/core/compress_offload.c > > @@ -134,6 +134,7 @@ static int snd_compr_open(struct inode *inode, > > struct file *f) > > } > > runtime->state = SNDRV_PCM_STATE_OPEN; > > init_waitqueue_head(&runtime->sleep); > > + INIT_LIST_HEAD(&runtime->tasks); > > Thanks. > > > data->stream.runtime = runtime; > > f->private_data = (void *)data; > > scoped_guard(mutex, &compr->lock) > > @@ -1003,10 +1004,6 @@ static struct snd_compr_task_runtime * > > > > static void snd_compr_task_free(struct snd_compr_task_runtime *task) > > { > > - if (task->output) > > - dma_buf_put(task->output); > > - if (task->input) > > - dma_buf_put(task->input); > > kfree(task); > > } > > See bellow. > > > @@ -1045,6 +1042,7 @@ static int snd_compr_task_new(struct > > snd_compr_stream *stream, struct snd_compr_ > > retval = utask->output_fd; > > goto cleanup; > > } > > + utask->seqno = task->seqno; > > Thanks. > > > list_add_tail(&task->list, &stream->runtime->tasks); > > stream->runtime->total_tasks++; > > return 0; > > > > There is no dma_buf_get() called, so remove the dma_buf_put(). > > I expected that the driver will increase this reference counter in the > task_create callback. But yes, it will be probably better to do in > snd_compr_task_new() when file descriptors are used. > > I will send v3 soon. Thank you for your comments. Thanks, So when can we get the v3? Best regards Shengjiu Wang > > Jaroslav > > -- > Jaroslav Kysela <perex@perex.cz> > Linux Sound Maintainer; ALSA Project; Red Hat, Inc. >
On 21. 06. 24 4:00, Shengjiu Wang wrote: >> I expected that the driver will increase this reference counter in the >> task_create callback. But yes, it will be probably better to do in >> snd_compr_task_new() when file descriptors are used. >> >> I will send v3 soon. Thank you for your comments. > > Thanks, So when can we get the v3? V3 is out. Thanks for the ping. Jaroslav
diff --git a/Documentation/sound/designs/compress-passthrough.rst b/Documentation/sound/designs/compress-passthrough.rst new file mode 100644 index 000000000000..975462500c33 --- /dev/null +++ b/Documentation/sound/designs/compress-passthrough.rst @@ -0,0 +1,125 @@ +================================= +ALSA Co-processor Passthrough API +================================= + +Jaroslav Kysela <perex@perex.cz> + + +Overview +======== + +There is a requirement to expose the audio hardware that accelerates various +tasks for user space such as sample rate converters, compressed +stream decoders, etc. + +This is description for the API extension for the compress ALSA API which +is able to handle "tasks" that are not bound to real-time operations +and allows for the serialization of operations. + +Requirements +============ + +The main requirements are: + +- serialization of multiple tasks for user space to allow multiple + operations without user space intervention + +- separate buffers (input + output) for each operation + +- expose buffers using mmap to user space + +- signal user space when the task is finished (standard poll mechanism) + +Design +====== + +A new direction SND_COMPRESS_PASSTHROUGH is introduced to identify +the passthrough API. + +The API extension shares device enumeration and parameters handling from +the main compressed API. All other realtime streaming ioctls are deactivated +and a new set of task related ioctls are introduced. The standard +read/write/mmap I/O operations are not supported in the passthrough device. + +Device ("stream") state handling is reduced to OPEN/SETUP. All other +states are not available for the passthrough mode. + +Data I/O mechanism is using standard dma-buf interface with all advantages +like mmap, standard I/O, buffer sharing etc. One buffer is used for the +input data and second (separate) buffer is used for the output data. Each task +have separate I/O buffers. + +For the buffering parameters, the fragments means a limit of allocated tasks +for given device. The fragment_size limits the input buffer size for the given +device. The output buffer size is determined by the driver (may be different +from the input buffer size). + +State Machine +============= + +The passthrough audio stream state machine is described below : + + +----------+ + | | + | OPEN | + | | + +----------+ + | + | + | compr_set_params() + | + v + all passthrough task ops +----------+ + +------------------------------------| | + | | SETUP | + | | + | +----------+ + | | + +------------------------------------------+ + + +Passthrough operations (ioctls) +=============================== + +CREATE +------ +Creates a set of input/output buffers. The input buffer size is +fragment_size. Allocates unique seqno. + +The hardware drivers allocate internal 'struct dma_buf' for both input and +output buffers (using 'dma_buf_export()' function). The anonymous +file descriptors for those buffers are passed to user space. + +FREE +---- +Free a set of input/output buffers. If a task is active, the stop +operation is executed before. If seqno is zero, operation is executed for all +tasks. + +START +----- +Starts (queues) a task. There are two cases of the task start - right after +the task is created. In this case, origin_seqno must be zero. +The second case is for reusing of already finished task. The origin_seqno +must identify the task to be reused. In both cases, a new seqno value +is allocated and returned to user space. + +The prerequisite is that application filled input dma buffer with +new source data and set input_size to pass the real data size to the driver. + +The order of data processing is preserved (first started job must be +finished at first). + +STOP +---- +Stop (dequeues) a task. If seqno is zero, operation is executed for all +tasks. + +STATUS +------ +Obtain the task status (active, finished). Also, the driver will set +the real output data size (valid area in the output buffer). + +Credits +======= +- ... diff --git a/include/sound/compress_driver.h b/include/sound/compress_driver.h index bcf872c17dd3..2884b1e7955d 100644 --- a/include/sound/compress_driver.h +++ b/include/sound/compress_driver.h @@ -19,6 +19,22 @@ struct snd_compr_ops; +/** + * struct snd_compr_task_runtime: task runtime description + * + */ +struct snd_compr_task_runtime { + struct list_head list; + struct dma_buf *input; + struct dma_buf *output; + u64 seqno; + u64 input_size; + u64 output_size; + u8 state; + void *private_value; +}; + + /** * struct snd_compr_runtime: runtime stream description * @state: stream state @@ -54,6 +70,11 @@ struct snd_compr_runtime { dma_addr_t dma_addr; size_t dma_bytes; struct snd_dma_buffer *dma_buffer_p; + + u32 active_tasks; + u32 total_tasks; + u64 task_seqno; + struct list_head tasks; }; /** @@ -132,6 +153,12 @@ struct snd_compr_ops { struct snd_compr_caps *caps); int (*get_codec_caps) (struct snd_compr_stream *stream, struct snd_compr_codec_caps *codec); +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) + int (*task_create) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); + int (*task_start) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); + int (*task_stop) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); + int (*task_free) (struct snd_compr_stream *stream, struct snd_compr_task_runtime *task); +#endif }; /** @@ -242,4 +269,9 @@ int snd_compr_free_pages(struct snd_compr_stream *stream); int snd_compr_stop_error(struct snd_compr_stream *stream, snd_pcm_state_t state); +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) +void snd_compr_task_finished(struct snd_compr_stream *stream, + struct snd_compr_task_runtime *task); +#endif + #endif diff --git a/include/uapi/sound/compress_offload.h b/include/uapi/sound/compress_offload.h index d185957f3fe0..5fed1979522b 100644 --- a/include/uapi/sound/compress_offload.h +++ b/include/uapi/sound/compress_offload.h @@ -1,4 +1,4 @@ -/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ + /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ /* * compress_offload.h - compress offload header definations * @@ -14,7 +14,7 @@ #include <sound/compress_params.h> -#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 2, 0) +#define SNDRV_COMPRESS_VERSION SNDRV_PROTOCOL_VERSION(0, 3, 0) /** * struct snd_compressed_buffer - compressed buffer * @fragment_size: size of buffer fragment in bytes @@ -68,7 +68,8 @@ struct snd_compr_avail { enum snd_compr_direction { SND_COMPRESS_PLAYBACK = 0, - SND_COMPRESS_CAPTURE + SND_COMPRESS_CAPTURE, + SND_COMPRESS_PASSTHROUGH }; /** @@ -127,6 +128,42 @@ struct snd_compr_metadata { __u32 value[8]; } __attribute__((packed, aligned(4))); +/** + * struct snd_compr_task - task primitive for non-realtime operation + * @seqno: sequence number (task identifier) + * @origin_seqno: previous sequence number (task identifier) - for reuse + * @input_fd: data input file descriptor (dma-buf) + * @output_fd: data output file descriptor (dma-buf) + * @input_size: filled data in bytes (from caller, must not exceed fragment size) + */ +struct snd_compr_task { + __u64 seqno; + __u64 origin_seqno; + int input_fd; + int output_fd; + __u64 input_size; + __u8 reserved[16]; +} __attribute__((packed, aligned(4))); + +enum snd_compr_state { + SND_COMPRESS_TASK_STATE_IDLE = 0, + SND_COMPRESS_TASK_STATE_ACTIVE, + SND_COMPRESS_TASK_STATE_FINISHED +}; + +/** + * struct snd_compr_task_status - task status + * @seqno: sequence number (task identifier) + * @output_size: filled data in bytes (from driver) + * @state: actual task state (SND_COMPRESS_TASK_STATE_*) + */ +struct snd_compr_task_status { + __u64 seqno; + __u64 output_size; + __u8 state; + __u8 reserved[15]; +} __attribute__((packed, aligned(4))); + /* * compress path ioctl definitions * SNDRV_COMPRESS_GET_CAPS: Query capability of DSP @@ -164,6 +201,14 @@ struct snd_compr_metadata { #define SNDRV_COMPRESS_DRAIN _IO('C', 0x34) #define SNDRV_COMPRESS_NEXT_TRACK _IO('C', 0x35) #define SNDRV_COMPRESS_PARTIAL_DRAIN _IO('C', 0x36) + + +#define SNDRV_COMPRESS_TASK_CREATE _IOWR('C', 0x60, struct snd_compr_task) +#define SNDRV_COMPRESS_TASK_FREE _IOW('C', 0x61, __u64) +#define SNDRV_COMPRESS_TASK_START _IOWR('C', 0x62, struct snd_compr_task) +#define SNDRV_COMPRESS_TASK_STOP _IOW('C', 0x63, __u64) +#define SNDRV_COMPRESS_TASK_STATUS _IOWR('C', 0x68, struct snd_compr_task_status) + /* * TODO * 1. add mmap support diff --git a/sound/core/Kconfig b/sound/core/Kconfig index 8077f481d84f..3541fe6d477f 100644 --- a/sound/core/Kconfig +++ b/sound/core/Kconfig @@ -59,6 +59,10 @@ config SND_CORE_TEST config SND_COMPRESS_OFFLOAD tristate +config SND_COMPRESS_PASSTHROUGH + select DMA_BUF + tristate + config SND_JACK bool diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c index f0008fa2d839..da048e61c574 100644 --- a/sound/core/compress_offload.c +++ b/sound/core/compress_offload.c @@ -24,6 +24,7 @@ #include <linux/types.h> #include <linux/uio.h> #include <linux/uaccess.h> +#include <linux/dma-buf.h> #include <linux/module.h> #include <linux/compat.h> #include <sound/core.h> @@ -54,6 +55,12 @@ struct snd_compr_file { static void error_delayed_work(struct work_struct *work); +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) +static void snd_compr_task_free_all(struct snd_compr_stream *stream); +#else +static inline void snd_compr_task_free_all(struct snd_compr_stream *stream) { } +#endif + /* * a note on stream states used: * we use following states in the compressed core @@ -85,6 +92,8 @@ static int snd_compr_open(struct inode *inode, struct file *f) dirn = SND_COMPRESS_PLAYBACK; else if ((f->f_flags & O_ACCMODE) == O_RDONLY) dirn = SND_COMPRESS_CAPTURE; + else if ((f->f_flags & O_ACCMODE) == O_RDWR) + dirn = SND_COMPRESS_PASSTHROUGH; else return -EINVAL; @@ -154,6 +163,8 @@ static int snd_compr_free(struct inode *inode, struct file *f) break; } + snd_compr_task_free_all(&data->stream); + data->stream.ops->free(&data->stream); if (!data->stream.runtime->dma_buffer_p) kfree(data->stream.runtime->buffer); @@ -226,6 +237,9 @@ snd_compr_ioctl_avail(struct snd_compr_stream *stream, unsigned long arg) struct snd_compr_avail ioctl_avail; size_t avail; + if (stream->direction == SND_COMPRESS_PASSTHROUGH) + return -EBADFD; + avail = snd_compr_calc_avail(stream, &ioctl_avail); ioctl_avail.avail = avail; @@ -287,6 +301,8 @@ static ssize_t snd_compr_write(struct file *f, const char __user *buf, return -EFAULT; stream = &data->stream; + if (stream->direction == SND_COMPRESS_PASSTHROUGH) + return -EBADFD; guard(mutex)(&stream->device->lock); /* write is allowed when stream is running or has been steup */ switch (stream->runtime->state) { @@ -336,6 +352,8 @@ static ssize_t snd_compr_read(struct file *f, char __user *buf, return -EFAULT; stream = &data->stream; + if (stream->direction == SND_COMPRESS_PASSTHROUGH) + return -EBADFD; guard(mutex)(&stream->device->lock); /* read is allowed when stream is running, paused, draining and setup @@ -385,6 +403,8 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) { struct snd_compr_file *data = f->private_data; struct snd_compr_stream *stream; + struct snd_compr_runtime *runtime; + struct snd_compr_task_runtime *task; size_t avail; __poll_t retval = 0; @@ -392,6 +412,7 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) return EPOLLERR; stream = &data->stream; + runtime = stream->runtime; guard(mutex)(&stream->device->lock); @@ -405,6 +426,18 @@ static __poll_t snd_compr_poll(struct file *f, poll_table *wait) poll_wait(f, &stream->runtime->sleep, wait); + if (stream->direction == SND_COMPRESS_PASSTHROUGH) { + if (runtime->fragments > runtime->active_tasks) + retval |= EPOLLOUT | EPOLLWRNORM; + task = list_first_entry_or_null(&runtime->tasks, + struct snd_compr_task_runtime, + list); + if (task && task->state == SND_COMPRESS_TASK_STATE_FINISHED) + retval |= EPOLLIN | EPOLLRDNORM; + return retval; + } + + avail = snd_compr_get_avail(stream); pr_debug("avail is %ld\n", (unsigned long)avail); /* check if we have at least one fragment to fill */ @@ -521,6 +554,9 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream, unsigned int buffer_size; void *buffer = NULL; + if (stream->direction == SND_COMPRESS_PASSTHROUGH) + goto params; + buffer_size = params->buffer.fragment_size * params->buffer.fragments; if (stream->ops->copy) { buffer = NULL; @@ -543,18 +579,30 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream, if (!buffer) return -ENOMEM; } - stream->runtime->fragment_size = params->buffer.fragment_size; - stream->runtime->fragments = params->buffer.fragments; + stream->runtime->buffer = buffer; stream->runtime->buffer_size = buffer_size; +params: + stream->runtime->fragment_size = params->buffer.fragment_size; + stream->runtime->fragments = params->buffer.fragments; return 0; } -static int snd_compress_check_input(struct snd_compr_params *params) +static int +snd_compress_check_input(struct snd_compr_stream *stream, struct snd_compr_params *params) { + u32 max_fragments; + /* first let's check the buffer parameter's */ - if (params->buffer.fragment_size == 0 || - params->buffer.fragments > U32_MAX / params->buffer.fragment_size || + if (params->buffer.fragment_size == 0) + return -EINVAL; + + if (stream->direction == SND_COMPRESS_PASSTHROUGH) + max_fragments = 64; /* safe value */ + else + max_fragments = U32_MAX / params->buffer.fragment_size; + + if (params->buffer.fragments > max_fragments || params->buffer.fragments == 0) return -EINVAL; @@ -583,7 +631,7 @@ snd_compr_set_params(struct snd_compr_stream *stream, unsigned long arg) if (IS_ERR(params)) return PTR_ERR(no_free_ptr(params)); - retval = snd_compress_check_input(params); + retval = snd_compress_check_input(stream, params); if (retval) return retval; @@ -939,6 +987,259 @@ static int snd_compr_partial_drain(struct snd_compr_stream *stream) return snd_compress_wait_for_drain(stream); } +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) + +static struct snd_compr_task_runtime * + snd_compr_find_task(struct snd_compr_stream *stream, __u64 seqno) +{ + struct snd_compr_task_runtime *task; + + list_for_each_entry(task, &stream->runtime->tasks, list) { + if (task->seqno == seqno) + return task; + } + return NULL; +} + +static void snd_compr_task_free(struct snd_compr_task_runtime *task) +{ + if (task->output) + dma_buf_put(task->output); + if (task->input) + dma_buf_put(task->input); + kfree(task); +} + +static u64 snd_compr_seqno_next(struct snd_compr_stream *stream) +{ + u64 seqno = ++stream->runtime->task_seqno; + if (seqno == 0) + seqno = ++stream->runtime->task_seqno; + return seqno; +} + +static int snd_compr_task_new(struct snd_compr_stream *stream, struct snd_compr_task *utask) +{ + struct snd_compr_task_runtime *task; + int retval; + + if (stream->runtime->total_tasks >= stream->runtime->fragments) + return -EBUSY; + if (utask->origin_seqno != 0 || utask->input_size != 0) + return -EINVAL; + task = kzalloc(sizeof(*task), GFP_KERNEL); + if (task == NULL) + return -ENOMEM; + task->seqno = snd_compr_seqno_next(stream); + task->input_size = utask->input_size; + retval = stream->ops->task_create(stream, task); + if (retval < 0) + goto cleanup; + utask->input_fd = dma_buf_fd(task->input, O_WRONLY|O_CLOEXEC); + if (utask->input_fd < 0) { + retval = utask->input_fd; + goto cleanup; + } + utask->output_fd = dma_buf_fd(task->output, O_RDONLY|O_CLOEXEC); + if (utask->output_fd < 0) { + retval = utask->output_fd; + goto cleanup; + } + list_add_tail(&task->list, &stream->runtime->tasks); + stream->runtime->total_tasks++; + return 0; +cleanup: + snd_compr_task_free(task); + return retval; +} + +static int snd_compr_task_create(struct snd_compr_stream *stream, unsigned long arg) +{ + struct snd_compr_task *task __free(kfree) = NULL; + int retval; + + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) + return -EPERM; + task = memdup_user((void __user *)arg, sizeof(*task)); + if (IS_ERR(task)) + return PTR_ERR(no_free_ptr(task)); + retval = snd_compr_task_new(stream, task); + if (retval >= 0) + if (copy_to_user((void __user *)arg, task, sizeof(*task))) + retval = -EFAULT; + return retval; +} + +static int snd_compr_task_start_prepare(struct snd_compr_task_runtime *task, + struct snd_compr_task *utask) +{ + if (task == NULL) + return -EINVAL; + if (task->state >= SND_COMPRESS_TASK_STATE_FINISHED) + return -EBUSY; + if (utask->input_size > task->input->size) + return -EINVAL; + task->input_size = utask->input_size; + task->state = SND_COMPRESS_TASK_STATE_IDLE; + return 0; +} + +static int snd_compr_task_start(struct snd_compr_stream *stream, struct snd_compr_task *utask) +{ + struct snd_compr_task_runtime *task; + int retval; + + if (utask->origin_seqno > 0) { + task = snd_compr_find_task(stream, utask->seqno); + retval = snd_compr_task_start_prepare(task, utask); + if (retval < 0) + return retval; + task->seqno = utask->seqno = snd_compr_seqno_next(stream); + utask->origin_seqno = 0; + list_move_tail(&task->list, &stream->runtime->tasks); + } else { + task = snd_compr_find_task(stream, utask->seqno); + if (task && task->state != SND_COMPRESS_TASK_STATE_IDLE) + return -EBUSY; + retval = snd_compr_task_start_prepare(task, utask); + if (retval < 0) + return retval; + } + retval = stream->ops->task_start(stream, task); + if (retval >= 0) { + task->state = SND_COMPRESS_TASK_STATE_ACTIVE; + stream->runtime->active_tasks++; + } + return retval; +} + +static int snd_compr_task_start_ioctl(struct snd_compr_stream *stream, unsigned long arg) +{ + struct snd_compr_task *task __free(kfree) = NULL; + int retval; + + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) + return -EPERM; + task = memdup_user((void __user *)arg, sizeof(*task)); + if (IS_ERR(task)) + return PTR_ERR(no_free_ptr(task)); + retval = snd_compr_task_start(stream, task); + if (retval >= 0) + if (copy_to_user((void __user *)arg, task, sizeof(*task))) + retval = -EFAULT; + return retval; +} + +static void snd_compr_task_stop_one(struct snd_compr_stream *stream, + struct snd_compr_task_runtime *task) +{ + if (task->state != SND_COMPRESS_TASK_STATE_ACTIVE) + return; + stream->ops->task_stop(stream, task); + if (!snd_BUG_ON(stream->runtime->active_tasks == 0)) + stream->runtime->active_tasks--; + list_move_tail(&task->list, &stream->runtime->tasks); + task->state = SND_COMPRESS_TASK_STATE_IDLE; +} + +static void snd_compr_task_free_one(struct snd_compr_stream *stream, + struct snd_compr_task_runtime *task) +{ + snd_compr_task_stop_one(stream, task); + stream->ops->task_free(stream, task); + list_del(&task->list); + snd_compr_task_free(task); + stream->runtime->total_tasks--; +} + +static void snd_compr_task_free_all(struct snd_compr_stream *stream) +{ + struct snd_compr_task_runtime *task; + + list_for_each_entry(task, &stream->runtime->tasks, list) + snd_compr_task_free_one(stream, task); +} + +typedef void (*snd_compr_seq_func_t)(struct snd_compr_stream *stream, + struct snd_compr_task_runtime *task); + +static int snd_compr_task_seq(struct snd_compr_stream *stream, unsigned long arg, + snd_compr_seq_func_t fcn) +{ + struct snd_compr_task_runtime *task; + __u64 seqno; + int retval; + + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) + return -EPERM; + retval = get_user(seqno, (__u64 __user *)arg); + if (retval < 0) + return retval; + retval = 0; + if (seqno == 0) { + list_for_each_entry(task, &stream->runtime->tasks, list) + fcn(stream, task); + } else { + task = snd_compr_find_task(stream, seqno); + if (task == NULL) { + retval = -EINVAL; + } else { + fcn(stream, task); + } + } + return retval; +} + +static int snd_compr_task_status(struct snd_compr_stream *stream, + struct snd_compr_task_status *status) +{ + struct snd_compr_task_runtime *task; + + task = snd_compr_find_task(stream, status->seqno); + if (task == NULL) + return -EINVAL; + status->output_size = task->output_size; + status->state = task->state; + return 0; +} + +static int snd_compr_task_status_ioctl(struct snd_compr_stream *stream, unsigned long arg) +{ + struct snd_compr_task_status *status __free(kfree) = NULL; + int retval; + + if (stream->runtime->state != SNDRV_PCM_STATE_SETUP) + return -EPERM; + status = memdup_user((void __user *)arg, sizeof(*status)); + if (IS_ERR(status)) + return PTR_ERR(no_free_ptr(status)); + retval = snd_compr_task_status(stream, status); + if (retval >= 0) + if (copy_to_user((void __user *)arg, status, sizeof(*status))) + retval = -EFAULT; + return retval; +} + +/** + * snd_compr_task_finished: Notify that the task was finished + * @stream: pointer to stream + * @task: runtime task structure + * + * Set the finished task state and notify waiters. + */ +void snd_compr_task_finished(struct snd_compr_stream *stream, + struct snd_compr_task_runtime *task) +{ + guard(mutex)(&stream->device->lock); + if (!snd_BUG_ON(stream->runtime->active_tasks == 0)) + stream->runtime->active_tasks--; + task->state = SND_COMPRESS_TASK_STATE_FINISHED; + wake_up(&stream->runtime->sleep); +} +EXPORT_SYMBOL(snd_compr_task_finished); + +#endif /* CONFIG_COMPRESS_PASSTHROUGH */ + static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg) { struct snd_compr_file *data = f->private_data; @@ -968,6 +1269,27 @@ static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg) return snd_compr_set_metadata(stream, arg); case _IOC_NR(SNDRV_COMPRESS_GET_METADATA): return snd_compr_get_metadata(stream, arg); + } + + if (stream->direction == SND_COMPRESS_PASSTHROUGH) { +#if IS_ENABLED(CONFIG_SND_COMPRESS_PASSTHROUGH) + switch (_IOC_NR(cmd)) { + case _IOC_NR(SNDRV_COMPRESS_TASK_CREATE): + return snd_compr_task_create(stream, arg); + case _IOC_NR(SNDRV_COMPRESS_TASK_FREE): + return snd_compr_task_seq(stream, arg, snd_compr_task_free_one); + case _IOC_NR(SNDRV_COMPRESS_TASK_START): + return snd_compr_task_start_ioctl(stream, arg); + case _IOC_NR(SNDRV_COMPRESS_TASK_STOP): + return snd_compr_task_seq(stream, arg, snd_compr_task_stop_one); + case _IOC_NR(SNDRV_COMPRESS_TASK_STATUS): + return snd_compr_task_status_ioctl(stream, arg); + } +#endif + return -ENOTTY; + } + + switch (_IOC_NR(cmd)) { case _IOC_NR(SNDRV_COMPRESS_TSTAMP): return snd_compr_tstamp(stream, arg); case _IOC_NR(SNDRV_COMPRESS_AVAIL):
There is a requirement to expose the audio hardware that accelerates various tasks for user space such as sample rate converters, compressed stream decoders, etc. This is description for the API extension for the compress ALSA API which is able to handle "tasks" that are not bound to real-time operations and allows for the serialization of operations. For details, refer to "compress-passthrough.rst" document. Note: This code is RFC (not tested, just to clearify the API requirements). My goal is to add a test (loopback) driver and add a support to tinycompress library in the next step. Cc: Mark Brown <broonie@kernel.org> Cc: Shengjiu Wang <shengjiu.wang@gmail.com> Cc: Nicolas Dufresne <nicolas@ndufresne.ca> Cc: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com> Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Cc: Vinod Koul <vkoul@kernel.org> Signed-off-by: Jaroslav Kysela <perex@perex.cz> --- v1..v2: - fix some documentation typos (thanks Amadeusz Sławiński) - fix memdup_user() error handling (thanks Takashi) - use one state variable instead multiple (thanks Takashi) - handle task limit (set to 64 - mentioned in documentation, NIY) - fix file release (free all tasks) --- .../sound/designs/compress-passthrough.rst | 125 +++++++ include/sound/compress_driver.h | 32 ++ include/uapi/sound/compress_offload.h | 51 ++- sound/core/Kconfig | 4 + sound/core/compress_offload.c | 334 +++++++++++++++++- 5 files changed, 537 insertions(+), 9 deletions(-) create mode 100644 Documentation/sound/designs/compress-passthrough.rst