| Message ID | 20230502115010.986325-4-perex@perex.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | pcm: hw: implement explicit silencing for snd_pcm_drain | expand |
On Tue, May 02, 2023 at 01:50:09PM +0200, Jaroslav Kysela wrote: >The driver may not require to touch the sample stream > "touching" >for the drain operation at all. >Handle this situation in alsa-lib. > this is weird without already knowing the context. i'd instead write: Handle the driver informing us that it is not necessary to set up silencing upon playback draining. This will be the case for drivers which are guaranteed to not read any samples beyond the application pointer. >--- a/src/pcm/pcm.c >+++ b/src/pcm/pcm.c >@@ -3707,6 +3707,29 @@ int snd_pcm_hw_params_can_disable_period_wakeup(const snd_pcm_hw_params_t *param > return !!(params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP); > } > >+/** >+ * \brief Check if hardware does perfect drain > "(is a) perfect drain" vs. "does draining". >+ * \param params Configuration space >+ * \retval 0 Hardware doesn't do perfect drain >+ * \retval 1 Hardware does perfect drain >+ * >+ * This function should only be called when the configuration space > "should be called only when" >+ * contains a single configuration. Call #snd_pcm_hw_params to choose >+ * a single configuration from the configuration space. >+ * >+ * The perfect drain means that the hardware does not use samples > see above. i guess one way to write it here would be "Perfect drain" means [...] >+ * beyond the stream application pointer. >+ */ regards
On Tue, 02 May 2023 13:50:09 +0200, Jaroslav Kysela wrote: > > The driver may not require to touch the sample stream > for the drain operation at all. Handle this situation > in alsa-lib. > > Signed-off-by: Jaroslav Kysela <perex@perex.cz> Ideally speaking, the checks and the setups of those new bits should be coupled with the PCM protocol version check (and the version bump). But it seems that you've already applied the series, and practically seen, those bits should be either not set or harmless, so let's cross fingers. thanks, Takashi
On 04. 05. 23 10:18, Takashi Iwai wrote: > On Tue, 02 May 2023 13:50:09 +0200, > Jaroslav Kysela wrote: >> >> The driver may not require to touch the sample stream >> for the drain operation at all. Handle this situation >> in alsa-lib. >> >> Signed-off-by: Jaroslav Kysela <perex@perex.cz> > > Ideally speaking, the checks and the setups of those new bits should > be coupled with the PCM protocol version check (and the version > bump). > > But it seems that you've already applied the series, and practically > seen, those bits should be either not set or harmless, so let's cross > fingers. Exactly, the current kernel code should skip those new flags, so they are used in alsa-lib only. It's just something like a "reservation" for the kernel space until things are really used there. We can bump the protocol version later (perhaps with other changes). Jaroslav
On Thu, 04 May 2023 10:31:50 +0200, Jaroslav Kysela wrote: > > On 04. 05. 23 10:18, Takashi Iwai wrote: > > On Tue, 02 May 2023 13:50:09 +0200, > > Jaroslav Kysela wrote: > >> > >> The driver may not require to touch the sample stream > >> for the drain operation at all. Handle this situation > >> in alsa-lib. > >> > >> Signed-off-by: Jaroslav Kysela <perex@perex.cz> > > > > Ideally speaking, the checks and the setups of those new bits should > > be coupled with the PCM protocol version check (and the version > > bump). > > > > But it seems that you've already applied the series, and practically > > seen, those bits should be either not set or harmless, so let's cross > > fingers. > > Exactly, the current kernel code should skip those new flags, so they > are used in alsa-lib only. It's just something like a "reservation" > for the kernel space until things are really used there. We can bump > the protocol version later (perhaps with other changes). If you'd like to include the new drain stuff in ALSA 1.2.9 release, we can take the uapi change to 6.4-rc1, too. But then let's bump the PCM protocol version along with it. So, if you think it's worth aligning with 6.4-rc1, let me know ASAP. I planned the submission to Linus in tomorrow, and I'd need to prepare and merge the uapi updates soon. thanks, Takashi
diff --git a/include/pcm.h b/include/pcm.h index b5a514fa..f15462d9 100644 --- a/include/pcm.h +++ b/include/pcm.h @@ -722,6 +722,7 @@ int snd_pcm_hw_params_is_half_duplex(const snd_pcm_hw_params_t *params); int snd_pcm_hw_params_is_joint_duplex(const snd_pcm_hw_params_t *params); int snd_pcm_hw_params_can_sync_start(const snd_pcm_hw_params_t *params); int snd_pcm_hw_params_can_disable_period_wakeup(const snd_pcm_hw_params_t *params); +int snd_pcm_hw_params_does_perfect_drain(const snd_pcm_hw_params_t *params); int snd_pcm_hw_params_supports_audio_wallclock_ts(const snd_pcm_hw_params_t *params); /* deprecated, use audio_ts_type */ int snd_pcm_hw_params_supports_audio_ts_type(const snd_pcm_hw_params_t *params, int type); int snd_pcm_hw_params_get_rate_numden(const snd_pcm_hw_params_t *params, diff --git a/include/sound/uapi/asound.h b/include/sound/uapi/asound.h index fc18c024..0b8834f2 100644 --- a/include/sound/uapi/asound.h +++ b/include/sound/uapi/asound.h @@ -281,6 +281,7 @@ typedef int __bitwise snd_pcm_subformat_t; #define SNDRV_PCM_INFO_DOUBLE 0x00000004 /* Double buffering needed for PCM start/stop */ #define SNDRV_PCM_INFO_BATCH 0x00000010 /* double buffering */ #define SNDRV_PCM_INFO_SYNC_APPLPTR 0x00000020 /* need the explicit sync of appl_ptr update */ +#define SNDRV_PCM_INFO_PERFECT_DRAIN 0x00000040 /* silencing at the end of stream is not required */ #define SNDRV_PCM_INFO_INTERLEAVED 0x00000100 /* channels are interleaved */ #define SNDRV_PCM_INFO_NONINTERLEAVED 0x00000200 /* channels are not interleaved */ #define SNDRV_PCM_INFO_COMPLEX 0x00000400 /* complex frame organization (mmap only) */ diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c index 88b13ed4..099d83ee 100644 --- a/src/pcm/pcm.c +++ b/src/pcm/pcm.c @@ -3707,6 +3707,29 @@ int snd_pcm_hw_params_can_disable_period_wakeup(const snd_pcm_hw_params_t *param return !!(params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP); } +/** + * \brief Check if hardware does perfect drain + * \param params Configuration space + * \retval 0 Hardware doesn't do perfect drain + * \retval 1 Hardware does perfect drain + * + * This function should only be called when the configuration space + * contains a single configuration. Call #snd_pcm_hw_params to choose + * a single configuration from the configuration space. + * + * The perfect drain means that the hardware does not use samples + * beyond the stream application pointer. + */ +int snd_pcm_hw_params_does_perfect_drain(const snd_pcm_hw_params_t *params) +{ + assert(params); + if (CHECK_SANITY(params->info == ~0U)) { + SNDMSG("invalid PCM info field"); + return 0; /* FIXME: should be a negative error? */ + } + return !!(params->info & SNDRV_PCM_INFO_PERFECT_DRAIN); +} + /** * \brief Check if hardware supports audio wallclock timestamps * \param params Configuration space diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c index 30ff843c..ea0c2ef2 100644 --- a/src/pcm/pcm_hw.c +++ b/src/pcm/pcm_hw.c @@ -99,6 +99,7 @@ typedef struct { struct snd_pcm_sync_ptr *sync_ptr; bool prepare_reset_sw_params; + bool perfect_drain; int period_event; snd_timer_t *period_timer; @@ -398,6 +399,7 @@ static int snd_pcm_hw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) params->info &= ~0xf0000000; if (pcm->tstamp_type != SND_PCM_TSTAMP_TYPE_GETTIMEOFDAY) params->info |= SND_PCM_INFO_MONOTONIC; + hw->perfect_drain = !!(params->info & SND_PCM_INFO_PERFECT_DRAIN); return query_status_data(hw); } @@ -739,7 +741,7 @@ static int snd_pcm_hw_drain(snd_pcm_t *pcm) if (pcm->stream != SND_PCM_STREAM_PLAYBACK) goto __skip_silence; - if (hw->drain_silence == 0) + if (hw->drain_silence == 0 || hw->perfect_drain) goto __skip_silence; snd_pcm_sw_params_current_no_lock(pcm, &sw_params); if (hw->drain_silence > 0) { diff --git a/src/pcm/pcm_local.h b/src/pcm/pcm_local.h index 4a859cd1..b039dda0 100644 --- a/src/pcm/pcm_local.h +++ b/src/pcm/pcm_local.h @@ -79,6 +79,8 @@ #define SND_PCM_INFO_DOUBLE SNDRV_PCM_INFO_DOUBLE /** device transfers samples in batch */ #define SND_PCM_INFO_BATCH SNDRV_PCM_INFO_BATCH +/** device does perfect drain (silencing not required) */ +#define SND_PCM_INFO_PERFECT_DRAIN SNDRV_PCM_INFO_PERFECT_DRAIN /** device accepts interleaved samples */ #define SND_PCM_INFO_INTERLEAVED SNDRV_PCM_INFO_INTERLEAVED /** device accepts non-interleaved samples */
The driver may not require to touch the sample stream for the drain operation at all. Handle this situation in alsa-lib. Signed-off-by: Jaroslav Kysela <perex@perex.cz> --- include/pcm.h | 1 + include/sound/uapi/asound.h | 1 + src/pcm/pcm.c | 23 +++++++++++++++++++++++ src/pcm/pcm_hw.c | 4 +++- src/pcm/pcm_local.h | 2 ++ 5 files changed, 30 insertions(+), 1 deletion(-)