| Message ID | 87lhp6n70k.wl%kuninori.morimoto.gx@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Dne 26.9.2014 v 10:03 Kuninori Morimoto napsal(a): > > Hi Clemens > > Thank you for your explain > >>> We noticed that DMA seems transfered +1 time when Ctrl-C happen. >>> But, is this correct ? is this our driver bug ? >>> [...] >>> 7. DMA transfer interrupt happen >>> >>> It calls snd_pcm_period_elapsed() and try to transfer next 2048 byte >>> snd_pcm_playback_avail() in snd_pcm_update_state() return 8192 this time. >>> then, it calls snd_pcm_drain_done() >>> >>> 9. snd_soc_dai_ops :: trigger called with SNDRV_PCM_TRIGGER_STOP >>> >>> driver stops DMA transfer >> >> There is no strong synchronization between snd_pcm_drain() and the rest >> of the system; snd_pcm_drain() just waits for an underrun to happen. >> >> In other words, the last actual DMA transfer is likely to contain >> invalid (outdated) samples, but gets aborted immediately. > > I wonder why we need drain ? > This "likely to contain invalid samples" will be solved if > we can skip "complete drain" ? The user app should do the flush instead the drain in this case... Jaroslav
Hi Jaroslav > >>> We noticed that DMA seems transfered +1 time when Ctrl-C happen. > >>> But, is this correct ? is this our driver bug ? > >>> [...] > >>> 7. DMA transfer interrupt happen > >>> > >>> It calls snd_pcm_period_elapsed() and try to transfer next 2048 byte > >>> snd_pcm_playback_avail() in snd_pcm_update_state() return 8192 this time. > >>> then, it calls snd_pcm_drain_done() > >>> > >>> 9. snd_soc_dai_ops :: trigger called with SNDRV_PCM_TRIGGER_STOP > >>> > >>> driver stops DMA transfer > >> > >> There is no strong synchronization between snd_pcm_drain() and the rest > >> of the system; snd_pcm_drain() just waits for an underrun to happen. > >> > >> In other words, the last actual DMA transfer is likely to contain > >> invalid (outdated) samples, but gets aborted immediately. > > > > I wonder why we need drain ? > > This "likely to contain invalid samples" will be solved if > > we can skip "complete drain" ? > > The user app should do the flush instead the drain in this case... Thank you about this help. Can you show me how to do this in app side ? (Calling some alsa-lib function ?) Best regards --- Kuninori Morimoto
Dne 26.9.2014 v 10:45 Kuninori Morimoto napsal(a): > > Hi Jaroslav > >>>>> We noticed that DMA seems transfered +1 time when Ctrl-C happen. >>>>> But, is this correct ? is this our driver bug ? >>>>> [...] >>>>> 7. DMA transfer interrupt happen >>>>> >>>>> It calls snd_pcm_period_elapsed() and try to transfer next 2048 byte >>>>> snd_pcm_playback_avail() in snd_pcm_update_state() return 8192 this time. >>>>> then, it calls snd_pcm_drain_done() >>>>> >>>>> 9. snd_soc_dai_ops :: trigger called with SNDRV_PCM_TRIGGER_STOP >>>>> >>>>> driver stops DMA transfer >>>> >>>> There is no strong synchronization between snd_pcm_drain() and the rest >>>> of the system; snd_pcm_drain() just waits for an underrun to happen. >>>> >>>> In other words, the last actual DMA transfer is likely to contain >>>> invalid (outdated) samples, but gets aborted immediately. >>> >>> I wonder why we need drain ? >>> This "likely to contain invalid samples" will be solved if >>> we can skip "complete drain" ? >> >> The user app should do the flush instead the drain in this case... > > Thank you about this help. > Can you show me how to do this in app side ? > (Calling some alsa-lib function ?) Yes, the function is snd_pcm_drop() . Jaroslav
Hi Jaroslav > >>>>> We noticed that DMA seems transfered +1 time when Ctrl-C happen. > >>>>> But, is this correct ? is this our driver bug ? > >>>>> [...] > >>>>> 7. DMA transfer interrupt happen > >>>>> > >>>>> It calls snd_pcm_period_elapsed() and try to transfer next 2048 byte > >>>>> snd_pcm_playback_avail() in snd_pcm_update_state() return 8192 this time. > >>>>> then, it calls snd_pcm_drain_done() > >>>>> > >>>>> 9. snd_soc_dai_ops :: trigger called with SNDRV_PCM_TRIGGER_STOP > >>>>> > >>>>> driver stops DMA transfer > >>>> > >>>> There is no strong synchronization between snd_pcm_drain() and the rest > >>>> of the system; snd_pcm_drain() just waits for an underrun to happen. > >>>> > >>>> In other words, the last actual DMA transfer is likely to contain > >>>> invalid (outdated) samples, but gets aborted immediately. > >>> > >>> I wonder why we need drain ? > >>> This "likely to contain invalid samples" will be solved if > >>> we can skip "complete drain" ? > >> > >> The user app should do the flush instead the drain in this case... > > > > Thank you about this help. > > Can you show me how to do this in app side ? > > (Calling some alsa-lib function ?) > > Yes, the function is snd_pcm_drop() . Thank you ! Best regards --- Kuninori Morimoto
diff --git a/include/sound/pcm.h b/include/sound/pcm.h index 6f3e10c..841a5e0 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -501,7 +501,7 @@ int snd_pcm_status(struct snd_pcm_substream *substream, struct snd_pcm_status *status); int snd_pcm_start(struct snd_pcm_substream *substream); int snd_pcm_stop(struct snd_pcm_substream *substream, snd_pcm_state_t status); -int snd_pcm_drain_done(struct snd_pcm_substream *substream); +int snd_pcm_drain_abort(struct snd_pcm_substream *substream); #ifdef CONFIG_PM int snd_pcm_suspend(struct snd_pcm_substream *substream); int snd_pcm_suspend_all(struct snd_pcm *pcm); diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 9acc77e..fbdbbde5 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -286,10 +286,8 @@ int snd_pcm_update_state(struct snd_pcm_substream *substream, if (avail > runtime->avail_max) runtime->avail_max = avail; if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) { - if (avail >= runtime->buffer_size) { - snd_pcm_drain_done(substream); - return -EPIPE; - } + snd_pcm_drain_abort(substream); + return -EPIPE; } else { if (avail >= runtime->stop_threshold) { xrun(substream); diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 8cd2f93..f3c48de 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -977,7 +977,7 @@ EXPORT_SYMBOL(snd_pcm_stop); * * Return: Zero if succesful, or a negative error code. */ -int snd_pcm_drain_done(struct snd_pcm_substream *substream) +int snd_pcm_drain_abort(struct snd_pcm_substream *substream) { return snd_pcm_action_single(&snd_pcm_action_stop, substream, SNDRV_PCM_STATE_SETUP);