From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: alsa-devel@alsa-project.org
Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Subject: [RFC PATCH 1/4] ALSA: core: let low-level driver or userspace disable rewinds
Date: Wed, 8 Jul 2015 05:10:33 -0500 [thread overview]
Message-ID: <1436350236-17509-2-git-send-email-pierre-louis.bossart@linux.intel.com> (raw)
In-Reply-To: <1436350236-17509-1-git-send-email-pierre-louis.bossart@linux.intel.com>
Add new hw_params flag to explicitly tell driver that rewinds
will never be used. This can be used by low-level driver to
optimize DMA operations and reduce power consumption.
Use this flag only when data written in ring buffer will
never be invalidated, e.g. any update of appl_ptr is final.
Caveat: there is currently no way to query capabilities without
opening a pcm stream, so applications might need to serially
open all exposed devices, check what they support by looking at
hw_params->info and close them (this is what PulseAudio does so
might not be an issue)
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
include/sound/pcm.h | 1 +
include/uapi/sound/asound.h | 1 +
sound/core/pcm_native.c | 8 ++++++++
3 files changed, 10 insertions(+)
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 691e7ee..25310b7 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -370,6 +370,7 @@ struct snd_pcm_runtime {
unsigned int rate_num;
unsigned int rate_den;
unsigned int no_period_wakeup: 1;
+ unsigned int no_rewinds:1;
/* -- SW params -- */
int tstamp_mode; /* mmap timestamp is updated */
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index a45be6b..b62b162 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -356,6 +356,7 @@ typedef int snd_pcm_hw_param_t;
#define SNDRV_PCM_HW_PARAMS_NORESAMPLE (1<<0) /* avoid rate resampling */
#define SNDRV_PCM_HW_PARAMS_EXPORT_BUFFER (1<<1) /* export buffer */
#define SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP (1<<2) /* disable period wakeups */
+#define SNDRV_PCM_HW_PARAMS_NO_REWINDS (1<<3) /* disable rewinds */
struct snd_interval {
unsigned int min, max;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index d126c03..a70e52d 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -543,6 +543,8 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
runtime->no_period_wakeup =
(params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP) &&
(params->flags & SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP);
+ runtime->no_rewinds =
+ params->flags & SNDRV_PCM_HW_PARAMS_NO_REWINDS;
bits = snd_pcm_format_physical_width(runtime->format);
runtime->sample_bits = bits;
@@ -2428,6 +2430,9 @@ static snd_pcm_sframes_t snd_pcm_playback_rewind(struct snd_pcm_substream *subst
if (frames == 0)
return 0;
+ if (runtime->no_rewinds)
+ return 0;
+
snd_pcm_stream_lock_irq(substream);
switch (runtime->status->state) {
case SNDRV_PCM_STATE_PREPARED:
@@ -2476,6 +2481,9 @@ static snd_pcm_sframes_t snd_pcm_capture_rewind(struct snd_pcm_substream *substr
if (frames == 0)
return 0;
+ if (runtime->no_rewinds)
+ return 0;
+
snd_pcm_stream_lock_irq(substream);
switch (runtime->status->state) {
case SNDRV_PCM_STATE_PREPARED:
--
1.9.1
next prev parent reply other threads:[~2015-07-08 10:10 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-08 10:10 [RFC PATCH 0/4] better support for bursty DMA usages Pierre-Louis Bossart
2015-07-08 10:10 ` Pierre-Louis Bossart [this message]
2015-07-08 14:21 ` [RFC PATCH 1/4] ALSA: core: let low-level driver or userspace disable rewinds Takashi Iwai
2015-07-08 16:58 ` Pierre-Louis Bossart
2015-07-11 17:06 ` Alexander E. Patrakov
2015-07-14 3:32 ` Raymond Yau
2015-07-14 17:39 ` Alexander E. Patrakov
2015-07-15 1:23 ` Raymond Yau
2015-07-15 4:51 ` Alexander E. Patrakov
2015-07-28 14:19 ` Pierre-Louis Bossart
2015-07-28 15:43 ` Alexander E. Patrakov
2015-07-29 17:46 ` Pierre-Louis Bossart
2015-07-30 6:11 ` Alexander E. Patrakov
2015-07-30 13:46 ` Pierre-Louis Bossart
2015-07-08 10:10 ` [RFC PATCH 2/4] ALSA: core: add .notify callback for pcm ops Pierre-Louis Bossart
2015-07-08 14:27 ` Takashi Iwai
2015-07-08 17:10 ` Pierre-Louis Bossart
2015-07-09 14:44 ` Takashi Iwai
2015-07-09 7:25 ` Raymond Yau
2015-07-09 7:35 ` Pierre-Louis Bossart
2015-07-08 10:10 ` [RFC PATCH 3/4] ALSA: core: add report of max dma burst Pierre-Louis Bossart
2015-07-08 14:37 ` Takashi Iwai
2015-07-08 17:46 ` Pierre-Louis Bossart
2015-07-10 2:35 ` Raymond Yau
2015-07-10 17:13 ` Lars-Peter Clausen
2015-07-11 17:46 ` Alexander E. Patrakov
2015-07-11 18:28 ` Jaroslav Kysela
2015-07-16 2:11 ` Raymond Yau
2015-07-08 10:10 ` [RFC PATCH 4/4] ALSA: hda: add default value for max_dma_burst Pierre-Louis Bossart
2015-07-08 14:31 ` [RFC PATCH 0/4] better support for bursty DMA usages Takashi Iwai
2015-07-08 17:50 ` Pierre-Louis Bossart
2015-07-15 10:14 ` Raymond Yau
2015-07-15 10:38 ` Alexander E. Patrakov
2015-07-22 14:44 ` Raymond Yau
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