| Message ID | 20250127044239.578540-5-quic_ekangupt@quicinc.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | misc: fastrpc: Add invokeV2 to support new features | expand |
On Mon, Jan 27, 2025 at 10:12:38AM +0530, Ekansh Gupta wrote: > For any remote call to DSP, after sending an invocation message, > fastRPC driver waits for glink response and during this time the > CPU can go into low power modes. Adding a polling mode support > with which fastRPC driver will poll continuously on a memory > after sending a message to remote subsystem which will eliminate > CPU wakeup and scheduling latencies and reduce fastRPC overhead. > With this change, DSP always sends a glink response which will > get ignored if polling mode didn't time out. Is there a chance to implement actual async I/O protocol with the help of the poll() call instead of hiding the polling / wait inside the invoke2? > > Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> > --- > drivers/misc/fastrpc.c | 122 +++++++++++++++++++++++++++++++++--- > include/uapi/misc/fastrpc.h | 3 +- > 2 files changed, 114 insertions(+), 11 deletions(-) > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > index cfacee0dded5..257a741af115 100644 > --- a/drivers/misc/fastrpc.c > +++ b/drivers/misc/fastrpc.c > @@ -19,6 +19,7 @@ > #include <linux/rpmsg.h> > #include <linux/scatterlist.h> > #include <linux/slab.h> > +#include <linux/delay.h> > #include <linux/firmware/qcom/qcom_scm.h> > #include <uapi/misc/fastrpc.h> > #include <linux/of_reserved_mem.h> > @@ -38,6 +39,7 @@ > #define FASTRPC_CTX_MAX (256) > #define FASTRPC_INIT_HANDLE 1 > #define FASTRPC_DSP_UTILITIES_HANDLE 2 > +#define FASTRPC_MAX_STATIC_HANDLE (20) > #define FASTRPC_CTXID_MASK (0xFF0) > #define INIT_FILELEN_MAX (2 * 1024 * 1024) > #define INIT_FILE_NAMELEN_MAX (128) > @@ -106,6 +108,19 @@ > > #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev) > > +/* Poll response number from remote processor for call completion */ > +#define FASTRPC_POLL_RESPONSE (0xdecaf) > +/* timeout in us for polling until memory barrier */ > +#define FASTRPC_POLL_TIME_MEM_UPDATE (500) > + > +/* Response types supported for RPC calls */ > +enum fastrpc_response_flags { > + /* normal job completion glink response */ > + NORMAL_RESPONSE = 0, > + /* process updates poll memory instead of glink response */ > + POLL_MODE = 1, > +}; > + > static const char *domains[FASTRPC_DEV_MAX] = { "adsp", "mdsp", > "sdsp", "cdsp", "cdsp1" }; > struct fastrpc_phy_page { > @@ -238,9 +253,16 @@ struct fastrpc_invoke_ctx { > u32 sc; > u64 *fdlist; > u32 *crclist; > + u32 *poll; > void __user *crc; > u64 ctxid; > u64 msg_sz; > + /* Threads poll for specified timeout and fall back to glink wait */ > + u64 poll_timeout; > + /* work done status flag */ > + bool is_work_done; > + /* response flags from remote processor */ > + enum fastrpc_response_flags rsp_flags; > struct kref refcount; > struct list_head node; /* list of ctxs */ > struct completion work; > @@ -258,6 +280,7 @@ struct fastrpc_invoke_ctx { > struct fastrpc_ctx_args { > struct fastrpc_invoke_args *args; > void __user *crc; > + u64 poll_timeout; > }; > > struct fastrpc_session_ctx { > @@ -619,11 +642,14 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc( > fastrpc_channel_ctx_get(cctx); > > ctx->crc = cargs->crc; > + ctx->poll_timeout = cargs->poll_timeout; > ctx->sc = sc; > ctx->retval = -1; > ctx->pid = current->pid; > ctx->client_id = user->client_id; > ctx->cctx = cctx; > + ctx->rsp_flags = NORMAL_RESPONSE; > + ctx->is_work_done = false; > init_completion(&ctx->work); > INIT_WORK(&ctx->put_work, fastrpc_context_put_wq); > > @@ -882,7 +908,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx) > sizeof(struct fastrpc_invoke_buf) + > sizeof(struct fastrpc_phy_page)) * ctx->nscalars + > sizeof(u64) * FASTRPC_MAX_FDLIST + > - sizeof(u32) * FASTRPC_MAX_CRCLIST; > + sizeof(u32) * FASTRPC_MAX_CRCLIST + > + sizeof(u32); > > return size; > } > @@ -975,6 +1002,8 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx) > pages = fastrpc_phy_page_start(list, ctx->nscalars); > ctx->fdlist = (u64 *)(pages + ctx->nscalars); > ctx->crclist = (u32 *)(ctx->fdlist + FASTRPC_MAX_FDLIST); > + ctx->poll = (u32 *)(ctx->crclist + FASTRPC_MAX_CRCLIST); > + > args = (uintptr_t)ctx->buf->virt + metalen; > rlen = pkt_size - metalen; > ctx->rpra = rpra; > @@ -1145,6 +1174,72 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx, > > } > > +static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx, u64 timeout) > +{ > + int err = -EIO, i, j; > + > + /* poll on memory for DSP response. Return failure on timeout */ > + for (i = 0, j = 0; i < timeout; i++, j++) { > + if (*ctx->poll == FASTRPC_POLL_RESPONSE) { > + err = 0; > + ctx->is_work_done = true; > + ctx->retval = 0; > + break; > + } > + if (j == FASTRPC_POLL_TIME_MEM_UPDATE) { > + /* make sure that all poll memory writes by DSP are seen by CPU */ > + dma_rmb(); > + j = 0; > + } > + udelay(1); > + } > + return err; > +} > + > +static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx, > + u32 kernel) > +{ > + int err = 0; > + > + if (kernel) { > + if (!wait_for_completion_timeout(&ctx->work, 10 * HZ)) > + err = -ETIMEDOUT; > + } else { > + err = wait_for_completion_interruptible(&ctx->work); > + } > + > + return err; > +} > + > +static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx, > + u32 kernel) > +{ > + int err; > + > + do { > + switch (ctx->rsp_flags) { > + case NORMAL_RESPONSE: > + err = fastrpc_wait_for_response(ctx, kernel); > + if (err || ctx->is_work_done) > + return err; > + break; > + case POLL_MODE: > + err = poll_for_remote_response(ctx, ctx->poll_timeout); > + /* If polling timed out, move to normal response mode */ > + if (err) > + ctx->rsp_flags = NORMAL_RESPONSE; > + break; > + default: > + err = -EBADR; > + dev_dbg(ctx->fl->sctx->dev, > + "unsupported response type:0x%x\n", ctx->rsp_flags); > + break; > + } > + } while (!ctx->is_work_done); > + > + return err; > +} > + > static int fastrpc_internal_invoke(struct fastrpc_user *fl, u32 kernel, > u32 handle, u32 sc, > struct fastrpc_ctx_args *cargs) > @@ -1180,16 +1275,20 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl, u32 kernel, > if (err) > goto bail; > > - if (kernel) { > - if (!wait_for_completion_timeout(&ctx->work, 10 * HZ)) > - err = -ETIMEDOUT; > - } else { > - err = wait_for_completion_interruptible(&ctx->work); > - } > + if (ctx->poll_timeout != 0 && handle > FASTRPC_MAX_STATIC_HANDLE > + && fl->pd == USER_PD) > + ctx->rsp_flags = POLL_MODE; > > + err = fastrpc_wait_for_completion(ctx, kernel); > if (err) > goto bail; > > + if (!ctx->is_work_done) { > + err = -ETIMEDOUT; > + dev_dbg(fl->sctx->dev, "Invalid workdone state for handle 0x%x, sc 0x%x\n", > + handle, sc); > + goto bail; > + } > /* make sure that all memory writes by DSP are seen by CPU */ > dma_rmb(); > /* populate all the output buffers with results */ > @@ -1769,7 +1868,7 @@ static int fastrpc_invokev2(struct fastrpc_user *fl, char __user *argp) > return -EFAULT; > > /* Check if all reserved fields are zero */ > - for (i = 0; i < 16; i++) { > + for (i = 0; i < 14; i++) { > if (inv2.reserved[i] != 0) > return -EINVAL; > } > @@ -1779,6 +1878,7 @@ static int fastrpc_invokev2(struct fastrpc_user *fl, char __user *argp) > return -ENOMEM; > > cargs->crc = (void __user *)(uintptr_t)inv2.crc; > + cargs->poll_timeout = inv2.poll_timeout; > > err = fastrpc_remote_invoke(fl, &inv2.inv, cargs); > kfree(cargs); > @@ -2581,12 +2681,14 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data, > ctx = idr_find(&cctx->ctx_idr, ctxid); > spin_unlock_irqrestore(&cctx->lock, flags); > > + /* Ignore this failure as context returned will be NULL for polling mode */ > if (!ctx) { > - dev_err(&rpdev->dev, "No context ID matches response\n"); > - return -ENOENT; > + dev_dbg(&rpdev->dev, "No context ID matches response\n"); > + return 0; > } > > ctx->retval = rsp->retval; > + ctx->is_work_done = true; > complete(&ctx->work); > > /* > diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h > index 406b80555d41..1920c537bbbf 100644 > --- a/include/uapi/misc/fastrpc.h > +++ b/include/uapi/misc/fastrpc.h > @@ -84,7 +84,8 @@ struct fastrpc_invoke { > struct fastrpc_invoke_v2 { > struct fastrpc_invoke inv; > __u64 crc; > - __u32 reserved[16]; > + __u64 poll_timeout; > + __u32 reserved[14]; > }; > > struct fastrpc_init_create { > -- > 2.34.1 >
On 1/29/2025 4:59 AM, Dmitry Baryshkov wrote: > On Mon, Jan 27, 2025 at 10:12:38AM +0530, Ekansh Gupta wrote: >> For any remote call to DSP, after sending an invocation message, >> fastRPC driver waits for glink response and during this time the >> CPU can go into low power modes. Adding a polling mode support >> with which fastRPC driver will poll continuously on a memory >> after sending a message to remote subsystem which will eliminate >> CPU wakeup and scheduling latencies and reduce fastRPC overhead. >> With this change, DSP always sends a glink response which will >> get ignored if polling mode didn't time out. > Is there a chance to implement actual async I/O protocol with the help > of the poll() call instead of hiding the polling / wait inside the > invoke2? This design is based on the implementation on DSP firmware as of today: Call flow: https://github.com/quic-ekangupt/fastrpc/blob/invokev2/Docs/invoke_v2.md#5-polling-mode Can you please give some reference to the async I/O protocol that you've suggested? I can check if it can be implemented here. --ekansh > >> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> >> --- >> drivers/misc/fastrpc.c | 122 +++++++++++++++++++++++++++++++++--- >> include/uapi/misc/fastrpc.h | 3 +- >> 2 files changed, 114 insertions(+), 11 deletions(-) >> >> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c >> index cfacee0dded5..257a741af115 100644 >> --- a/drivers/misc/fastrpc.c >> +++ b/drivers/misc/fastrpc.c >> @@ -19,6 +19,7 @@ >> #include <linux/rpmsg.h> >> #include <linux/scatterlist.h> >> #include <linux/slab.h> >> +#include <linux/delay.h> >> #include <linux/firmware/qcom/qcom_scm.h> >> #include <uapi/misc/fastrpc.h> >> #include <linux/of_reserved_mem.h> >> @@ -38,6 +39,7 @@ >> #define FASTRPC_CTX_MAX (256) >> #define FASTRPC_INIT_HANDLE 1 >> #define FASTRPC_DSP_UTILITIES_HANDLE 2 >> +#define FASTRPC_MAX_STATIC_HANDLE (20) >> #define FASTRPC_CTXID_MASK (0xFF0) >> #define INIT_FILELEN_MAX (2 * 1024 * 1024) >> #define INIT_FILE_NAMELEN_MAX (128) >> @@ -106,6 +108,19 @@ >> >> #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev) >> >> +/* Poll response number from remote processor for call completion */ >> +#define FASTRPC_POLL_RESPONSE (0xdecaf) >> +/* timeout in us for polling until memory barrier */ >> +#define FASTRPC_POLL_TIME_MEM_UPDATE (500) >> + >> +/* Response types supported for RPC calls */ >> +enum fastrpc_response_flags { >> + /* normal job completion glink response */ >> + NORMAL_RESPONSE = 0, >> + /* process updates poll memory instead of glink response */ >> + POLL_MODE = 1, >> +}; >> + >> static const char *domains[FASTRPC_DEV_MAX] = { "adsp", "mdsp", >> "sdsp", "cdsp", "cdsp1" }; >> struct fastrpc_phy_page { >> @@ -238,9 +253,16 @@ struct fastrpc_invoke_ctx { >> u32 sc; >> u64 *fdlist; >> u32 *crclist; >> + u32 *poll; >> void __user *crc; >> u64 ctxid; >> u64 msg_sz; >> + /* Threads poll for specified timeout and fall back to glink wait */ >> + u64 poll_timeout; >> + /* work done status flag */ >> + bool is_work_done; >> + /* response flags from remote processor */ >> + enum fastrpc_response_flags rsp_flags; >> struct kref refcount; >> struct list_head node; /* list of ctxs */ >> struct completion work; >> @@ -258,6 +280,7 @@ struct fastrpc_invoke_ctx { >> struct fastrpc_ctx_args { >> struct fastrpc_invoke_args *args; >> void __user *crc; >> + u64 poll_timeout; >> }; >> >> struct fastrpc_session_ctx { >> @@ -619,11 +642,14 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc( >> fastrpc_channel_ctx_get(cctx); >> >> ctx->crc = cargs->crc; >> + ctx->poll_timeout = cargs->poll_timeout; >> ctx->sc = sc; >> ctx->retval = -1; >> ctx->pid = current->pid; >> ctx->client_id = user->client_id; >> ctx->cctx = cctx; >> + ctx->rsp_flags = NORMAL_RESPONSE; >> + ctx->is_work_done = false; >> init_completion(&ctx->work); >> INIT_WORK(&ctx->put_work, fastrpc_context_put_wq); >> >> @@ -882,7 +908,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx) >> sizeof(struct fastrpc_invoke_buf) + >> sizeof(struct fastrpc_phy_page)) * ctx->nscalars + >> sizeof(u64) * FASTRPC_MAX_FDLIST + >> - sizeof(u32) * FASTRPC_MAX_CRCLIST; >> + sizeof(u32) * FASTRPC_MAX_CRCLIST + >> + sizeof(u32); >> >> return size; >> } >> @@ -975,6 +1002,8 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx) >> pages = fastrpc_phy_page_start(list, ctx->nscalars); >> ctx->fdlist = (u64 *)(pages + ctx->nscalars); >> ctx->crclist = (u32 *)(ctx->fdlist + FASTRPC_MAX_FDLIST); >> + ctx->poll = (u32 *)(ctx->crclist + FASTRPC_MAX_CRCLIST); >> + >> args = (uintptr_t)ctx->buf->virt + metalen; >> rlen = pkt_size - metalen; >> ctx->rpra = rpra; >> @@ -1145,6 +1174,72 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx, >> >> } >> >> +static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx, u64 timeout) >> +{ >> + int err = -EIO, i, j; >> + >> + /* poll on memory for DSP response. Return failure on timeout */ >> + for (i = 0, j = 0; i < timeout; i++, j++) { >> + if (*ctx->poll == FASTRPC_POLL_RESPONSE) { >> + err = 0; >> + ctx->is_work_done = true; >> + ctx->retval = 0; >> + break; >> + } >> + if (j == FASTRPC_POLL_TIME_MEM_UPDATE) { >> + /* make sure that all poll memory writes by DSP are seen by CPU */ >> + dma_rmb(); >> + j = 0; >> + } >> + udelay(1); >> + } >> + return err; >> +} >> + >> +static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx, >> + u32 kernel) >> +{ >> + int err = 0; >> + >> + if (kernel) { >> + if (!wait_for_completion_timeout(&ctx->work, 10 * HZ)) >> + err = -ETIMEDOUT; >> + } else { >> + err = wait_for_completion_interruptible(&ctx->work); >> + } >> + >> + return err; >> +} >> + >> +static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx, >> + u32 kernel) >> +{ >> + int err; >> + >> + do { >> + switch (ctx->rsp_flags) { >> + case NORMAL_RESPONSE: >> + err = fastrpc_wait_for_response(ctx, kernel); >> + if (err || ctx->is_work_done) >> + return err; >> + break; >> + case POLL_MODE: >> + err = poll_for_remote_response(ctx, ctx->poll_timeout); >> + /* If polling timed out, move to normal response mode */ >> + if (err) >> + ctx->rsp_flags = NORMAL_RESPONSE; >> + break; >> + default: >> + err = -EBADR; >> + dev_dbg(ctx->fl->sctx->dev, >> + "unsupported response type:0x%x\n", ctx->rsp_flags); >> + break; >> + } >> + } while (!ctx->is_work_done); >> + >> + return err; >> +} >> + >> static int fastrpc_internal_invoke(struct fastrpc_user *fl, u32 kernel, >> u32 handle, u32 sc, >> struct fastrpc_ctx_args *cargs) >> @@ -1180,16 +1275,20 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl, u32 kernel, >> if (err) >> goto bail; >> >> - if (kernel) { >> - if (!wait_for_completion_timeout(&ctx->work, 10 * HZ)) >> - err = -ETIMEDOUT; >> - } else { >> - err = wait_for_completion_interruptible(&ctx->work); >> - } >> + if (ctx->poll_timeout != 0 && handle > FASTRPC_MAX_STATIC_HANDLE >> + && fl->pd == USER_PD) >> + ctx->rsp_flags = POLL_MODE; >> >> + err = fastrpc_wait_for_completion(ctx, kernel); >> if (err) >> goto bail; >> >> + if (!ctx->is_work_done) { >> + err = -ETIMEDOUT; >> + dev_dbg(fl->sctx->dev, "Invalid workdone state for handle 0x%x, sc 0x%x\n", >> + handle, sc); >> + goto bail; >> + } >> /* make sure that all memory writes by DSP are seen by CPU */ >> dma_rmb(); >> /* populate all the output buffers with results */ >> @@ -1769,7 +1868,7 @@ static int fastrpc_invokev2(struct fastrpc_user *fl, char __user *argp) >> return -EFAULT; >> >> /* Check if all reserved fields are zero */ >> - for (i = 0; i < 16; i++) { >> + for (i = 0; i < 14; i++) { >> if (inv2.reserved[i] != 0) >> return -EINVAL; >> } >> @@ -1779,6 +1878,7 @@ static int fastrpc_invokev2(struct fastrpc_user *fl, char __user *argp) >> return -ENOMEM; >> >> cargs->crc = (void __user *)(uintptr_t)inv2.crc; >> + cargs->poll_timeout = inv2.poll_timeout; >> >> err = fastrpc_remote_invoke(fl, &inv2.inv, cargs); >> kfree(cargs); >> @@ -2581,12 +2681,14 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data, >> ctx = idr_find(&cctx->ctx_idr, ctxid); >> spin_unlock_irqrestore(&cctx->lock, flags); >> >> + /* Ignore this failure as context returned will be NULL for polling mode */ >> if (!ctx) { >> - dev_err(&rpdev->dev, "No context ID matches response\n"); >> - return -ENOENT; >> + dev_dbg(&rpdev->dev, "No context ID matches response\n"); >> + return 0; >> } >> >> ctx->retval = rsp->retval; >> + ctx->is_work_done = true; >> complete(&ctx->work); >> >> /* >> diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h >> index 406b80555d41..1920c537bbbf 100644 >> --- a/include/uapi/misc/fastrpc.h >> +++ b/include/uapi/misc/fastrpc.h >> @@ -84,7 +84,8 @@ struct fastrpc_invoke { >> struct fastrpc_invoke_v2 { >> struct fastrpc_invoke inv; >> __u64 crc; >> - __u32 reserved[16]; >> + __u64 poll_timeout; >> + __u32 reserved[14]; >> }; >> >> struct fastrpc_init_create { >> -- >> 2.34.1 >>
On Wed, Jan 29, 2025 at 11:12:16AM +0530, Ekansh Gupta wrote: > > > > On 1/29/2025 4:59 AM, Dmitry Baryshkov wrote: > > On Mon, Jan 27, 2025 at 10:12:38AM +0530, Ekansh Gupta wrote: > >> For any remote call to DSP, after sending an invocation message, > >> fastRPC driver waits for glink response and during this time the > >> CPU can go into low power modes. Adding a polling mode support > >> with which fastRPC driver will poll continuously on a memory > >> after sending a message to remote subsystem which will eliminate > >> CPU wakeup and scheduling latencies and reduce fastRPC overhead. > >> With this change, DSP always sends a glink response which will > >> get ignored if polling mode didn't time out. > > Is there a chance to implement actual async I/O protocol with the help > > of the poll() call instead of hiding the polling / wait inside the > > invoke2? > > This design is based on the implementation on DSP firmware as of today: > Call flow: https://github.com/quic-ekangupt/fastrpc/blob/invokev2/Docs/invoke_v2.md#5-polling-mode > > Can you please give some reference to the async I/O protocol that you've > suggested? I can check if it can be implemented here. As with the typical poll() call implementation: - write some data using ioctl - call poll() / select() to wait for the data to be processed - read data using another ioctl Getting back to your patch. from you commit message it is not clear, which SoCs support this feature. Reminding you that we are supporting all kinds of platforms, including the ones that are EoLed by Qualcomm. Next, you wrote that in-driver polling eliminates CPU wakeup and scheduling. However this should also increase power consumption. Is there any measurable difference in the latencies, granted that you already use ioctl() syscall, as such there will be two context switches. What is the actual impact?
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index cfacee0dded5..257a741af115 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -19,6 +19,7 @@ #include <linux/rpmsg.h> #include <linux/scatterlist.h> #include <linux/slab.h> +#include <linux/delay.h> #include <linux/firmware/qcom/qcom_scm.h> #include <uapi/misc/fastrpc.h> #include <linux/of_reserved_mem.h> @@ -38,6 +39,7 @@ #define FASTRPC_CTX_MAX (256) #define FASTRPC_INIT_HANDLE 1 #define FASTRPC_DSP_UTILITIES_HANDLE 2 +#define FASTRPC_MAX_STATIC_HANDLE (20) #define FASTRPC_CTXID_MASK (0xFF0) #define INIT_FILELEN_MAX (2 * 1024 * 1024) #define INIT_FILE_NAMELEN_MAX (128) @@ -106,6 +108,19 @@ #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev) +/* Poll response number from remote processor for call completion */ +#define FASTRPC_POLL_RESPONSE (0xdecaf) +/* timeout in us for polling until memory barrier */ +#define FASTRPC_POLL_TIME_MEM_UPDATE (500) + +/* Response types supported for RPC calls */ +enum fastrpc_response_flags { + /* normal job completion glink response */ + NORMAL_RESPONSE = 0, + /* process updates poll memory instead of glink response */ + POLL_MODE = 1, +}; + static const char *domains[FASTRPC_DEV_MAX] = { "adsp", "mdsp", "sdsp", "cdsp", "cdsp1" }; struct fastrpc_phy_page { @@ -238,9 +253,16 @@ struct fastrpc_invoke_ctx { u32 sc; u64 *fdlist; u32 *crclist; + u32 *poll; void __user *crc; u64 ctxid; u64 msg_sz; + /* Threads poll for specified timeout and fall back to glink wait */ + u64 poll_timeout; + /* work done status flag */ + bool is_work_done; + /* response flags from remote processor */ + enum fastrpc_response_flags rsp_flags; struct kref refcount; struct list_head node; /* list of ctxs */ struct completion work; @@ -258,6 +280,7 @@ struct fastrpc_invoke_ctx { struct fastrpc_ctx_args { struct fastrpc_invoke_args *args; void __user *crc; + u64 poll_timeout; }; struct fastrpc_session_ctx { @@ -619,11 +642,14 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc( fastrpc_channel_ctx_get(cctx); ctx->crc = cargs->crc; + ctx->poll_timeout = cargs->poll_timeout; ctx->sc = sc; ctx->retval = -1; ctx->pid = current->pid; ctx->client_id = user->client_id; ctx->cctx = cctx; + ctx->rsp_flags = NORMAL_RESPONSE; + ctx->is_work_done = false; init_completion(&ctx->work); INIT_WORK(&ctx->put_work, fastrpc_context_put_wq); @@ -882,7 +908,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx) sizeof(struct fastrpc_invoke_buf) + sizeof(struct fastrpc_phy_page)) * ctx->nscalars + sizeof(u64) * FASTRPC_MAX_FDLIST + - sizeof(u32) * FASTRPC_MAX_CRCLIST; + sizeof(u32) * FASTRPC_MAX_CRCLIST + + sizeof(u32); return size; } @@ -975,6 +1002,8 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx) pages = fastrpc_phy_page_start(list, ctx->nscalars); ctx->fdlist = (u64 *)(pages + ctx->nscalars); ctx->crclist = (u32 *)(ctx->fdlist + FASTRPC_MAX_FDLIST); + ctx->poll = (u32 *)(ctx->crclist + FASTRPC_MAX_CRCLIST); + args = (uintptr_t)ctx->buf->virt + metalen; rlen = pkt_size - metalen; ctx->rpra = rpra; @@ -1145,6 +1174,72 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx, } +static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx, u64 timeout) +{ + int err = -EIO, i, j; + + /* poll on memory for DSP response. Return failure on timeout */ + for (i = 0, j = 0; i < timeout; i++, j++) { + if (*ctx->poll == FASTRPC_POLL_RESPONSE) { + err = 0; + ctx->is_work_done = true; + ctx->retval = 0; + break; + } + if (j == FASTRPC_POLL_TIME_MEM_UPDATE) { + /* make sure that all poll memory writes by DSP are seen by CPU */ + dma_rmb(); + j = 0; + } + udelay(1); + } + return err; +} + +static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx, + u32 kernel) +{ + int err = 0; + + if (kernel) { + if (!wait_for_completion_timeout(&ctx->work, 10 * HZ)) + err = -ETIMEDOUT; + } else { + err = wait_for_completion_interruptible(&ctx->work); + } + + return err; +} + +static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx, + u32 kernel) +{ + int err; + + do { + switch (ctx->rsp_flags) { + case NORMAL_RESPONSE: + err = fastrpc_wait_for_response(ctx, kernel); + if (err || ctx->is_work_done) + return err; + break; + case POLL_MODE: + err = poll_for_remote_response(ctx, ctx->poll_timeout); + /* If polling timed out, move to normal response mode */ + if (err) + ctx->rsp_flags = NORMAL_RESPONSE; + break; + default: + err = -EBADR; + dev_dbg(ctx->fl->sctx->dev, + "unsupported response type:0x%x\n", ctx->rsp_flags); + break; + } + } while (!ctx->is_work_done); + + return err; +} + static int fastrpc_internal_invoke(struct fastrpc_user *fl, u32 kernel, u32 handle, u32 sc, struct fastrpc_ctx_args *cargs) @@ -1180,16 +1275,20 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl, u32 kernel, if (err) goto bail; - if (kernel) { - if (!wait_for_completion_timeout(&ctx->work, 10 * HZ)) - err = -ETIMEDOUT; - } else { - err = wait_for_completion_interruptible(&ctx->work); - } + if (ctx->poll_timeout != 0 && handle > FASTRPC_MAX_STATIC_HANDLE + && fl->pd == USER_PD) + ctx->rsp_flags = POLL_MODE; + err = fastrpc_wait_for_completion(ctx, kernel); if (err) goto bail; + if (!ctx->is_work_done) { + err = -ETIMEDOUT; + dev_dbg(fl->sctx->dev, "Invalid workdone state for handle 0x%x, sc 0x%x\n", + handle, sc); + goto bail; + } /* make sure that all memory writes by DSP are seen by CPU */ dma_rmb(); /* populate all the output buffers with results */ @@ -1769,7 +1868,7 @@ static int fastrpc_invokev2(struct fastrpc_user *fl, char __user *argp) return -EFAULT; /* Check if all reserved fields are zero */ - for (i = 0; i < 16; i++) { + for (i = 0; i < 14; i++) { if (inv2.reserved[i] != 0) return -EINVAL; } @@ -1779,6 +1878,7 @@ static int fastrpc_invokev2(struct fastrpc_user *fl, char __user *argp) return -ENOMEM; cargs->crc = (void __user *)(uintptr_t)inv2.crc; + cargs->poll_timeout = inv2.poll_timeout; err = fastrpc_remote_invoke(fl, &inv2.inv, cargs); kfree(cargs); @@ -2581,12 +2681,14 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data, ctx = idr_find(&cctx->ctx_idr, ctxid); spin_unlock_irqrestore(&cctx->lock, flags); + /* Ignore this failure as context returned will be NULL for polling mode */ if (!ctx) { - dev_err(&rpdev->dev, "No context ID matches response\n"); - return -ENOENT; + dev_dbg(&rpdev->dev, "No context ID matches response\n"); + return 0; } ctx->retval = rsp->retval; + ctx->is_work_done = true; complete(&ctx->work); /* diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h index 406b80555d41..1920c537bbbf 100644 --- a/include/uapi/misc/fastrpc.h +++ b/include/uapi/misc/fastrpc.h @@ -84,7 +84,8 @@ struct fastrpc_invoke { struct fastrpc_invoke_v2 { struct fastrpc_invoke inv; __u64 crc; - __u32 reserved[16]; + __u64 poll_timeout; + __u32 reserved[14]; }; struct fastrpc_init_create {
For any remote call to DSP, after sending an invocation message, fastRPC driver waits for glink response and during this time the CPU can go into low power modes. Adding a polling mode support with which fastRPC driver will poll continuously on a memory after sending a message to remote subsystem which will eliminate CPU wakeup and scheduling latencies and reduce fastRPC overhead. With this change, DSP always sends a glink response which will get ignored if polling mode didn't time out. Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> --- drivers/misc/fastrpc.c | 122 +++++++++++++++++++++++++++++++++--- include/uapi/misc/fastrpc.h | 3 +- 2 files changed, 114 insertions(+), 11 deletions(-)