[PATCH v2 0/3] ASoC: SOF: Intel: power optimizations with HDaudio SPIB register
This patchset was initially provided in a larger series that was split in two [1]. This part only provides support for the SPIB register support, added on Intel platforms since Skylake (2015).
The use of the SPIB register helps reduce power consumption - though to a smaller degree than DMI_L1. This hardware capability is however incompatible with userspace-initiated rewinds typically used by PulseAudio.
In the past (2015..2017) Intel suggested an API extension to let applications disable rewinds. At the time the feedback was that such a capability was too Intel-specific and SPIB remained unused except for loading DSP code. We now see devices with smaller batteries being released, and it's time to revisit Linux support for SPIB to extend battery life.
In this update the rewinds are disabled via an opt-in kernel parameter. In the previous reviews, there was consensus that a Kconfig option was too complicated for distributions to set, and we are missing a TBD API to expose such capabilities to user-space.
The debate on whether or not to use rewinds, and the impact of disabling rewinds, will likely be closed when Intel releases the 'deep-buffer' support, currently under development [2][3]. With this solution, rewinds will not be needed, ever. When an application deals with content that is not latency-sensitive (e.g. music playback), it will be able to reduce power consumption by selecting a different PCM device with increased buffering capabilities. Low-latency streams will be handled by the 'regular' path. In other words, the impossible compromise between power and latency will be handled with different PCM devices/profiles for the same endpoint, and we can push the design of capability negotiation to a later time when all the building blocks (firmware topology, kernel, userspace) are ready - we still have firmware xruns, DPCM race conditions to solve, and a need to describe these alternate PCM devices with UCM using 'modifiers'.
[1] https://lore.kernel.org/alsa-devel/20210610205326.1176400-1-pierre-louis.bos... [2] https://github.com/thesofproject/linux/pull/3146 [3] https://github.com/thesofproject/sof/pull/4611
Pierre-Louis Bossart (1): ALSA: pcm: introduce INFO_NO_REWINDS flag
Ranjani Sridharan (2): ASOC: SOF: pcm: add .ack callback support ASoC: SOF: Intel: add .ack support for HDaudio platforms
include/uapi/sound/asound.h | 2 +- sound/core/pcm_native.c | 2 ++ sound/soc/sof/intel/apl.c | 1 + sound/soc/sof/intel/cnl.c | 1 + sound/soc/sof/intel/hda-pcm.c | 41 ++++++++++++++++++++++++++++++-- sound/soc/sof/intel/hda-stream.c | 2 ++ sound/soc/sof/intel/hda.h | 1 + sound/soc/sof/intel/tgl.c | 1 + sound/soc/sof/ops.h | 10 ++++++++ sound/soc/sof/pcm.c | 9 +++++++ sound/soc/sof/sof-priv.h | 3 +++ 11 files changed, 70 insertions(+), 3 deletions(-)
When the hardware can only deal with a monotonically increasing appl_ptr, this flag can be set. In case the application requests a rewind, snd_pcm_rewind() will not return an error code but signal that the appl_ptr was not modified.
Reviewed-by: Péter Ujfalusi peter.ujfalusi@linux.intel.com Reviewed-by: Kai Vehmanen kai.vehmanen@linux.intel.com Reviewed-by: Ranjani Sridharan ranjani.sridharan@linux.intel.com Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- include/uapi/sound/asound.h | 2 +- sound/core/pcm_native.c | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index 1d84ec9db93b..bdb6f3c9db6c 100644 --- a/include/uapi/sound/asound.h +++ b/include/uapi/sound/asound.h @@ -300,7 +300,7 @@ typedef int __bitwise snd_pcm_subformat_t; #define SNDRV_PCM_INFO_HAS_LINK_ESTIMATED_ATIME 0x04000000 /* report estimated link audio time */ #define SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME 0x08000000 /* report synchronized audio/system time */ #define SNDRV_PCM_INFO_EXPLICIT_SYNC 0x10000000 /* needs explicit sync of pointers and data */ - +#define SNDRV_PCM_INFO_NO_REWINDS 0x20000000 /* hardware can only support monotonic changes of appl_ptr */ #define SNDRV_PCM_INFO_DRAIN_TRIGGER 0x40000000 /* internal kernel flag - trigger in drain */ #define SNDRV_PCM_INFO_FIFO_IN_FRAMES 0x80000000 /* internal kernel flag - FIFO size is in frames */
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index d233cb3b41d8..e3da2cc31a34 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -2905,6 +2905,8 @@ static snd_pcm_sframes_t snd_pcm_rewind(struct snd_pcm_substream *substream,
if (frames == 0) return 0; + if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) + return 0;
snd_pcm_stream_lock_irq(substream); ret = do_pcm_hwsync(substream);
On Mon, 04 Oct 2021 18:24:21 +0200, Pierre-Louis Bossart wrote:
When the hardware can only deal with a monotonically increasing appl_ptr, this flag can be set. In case the application requests a rewind, snd_pcm_rewind() will not return an error code but signal that the appl_ptr was not modified.
This modification itself is fine, but I guess that application may still move the appl_ptr directly via SNDRV_PCM_IOCTL_SYNC_PTR ioctl. We need to verify the backward move there, I suppose?
thanks,
Takashi
On 10/5/21 1:59 AM, Takashi Iwai wrote:
On Mon, 04 Oct 2021 18:24:21 +0200, Pierre-Louis Bossart wrote:
When the hardware can only deal with a monotonically increasing appl_ptr, this flag can be set. In case the application requests a rewind, snd_pcm_rewind() will not return an error code but signal that the appl_ptr was not modified.
This modification itself is fine, but I guess that application may still move the appl_ptr directly via SNDRV_PCM_IOCTL_SYNC_PTR ioctl. We need to verify the backward move there, I suppose?
Sorry Takashi, I wasn't able to fully follow your question.
In the previous version, I had an explicit check to see if the appl_ptr was modified by a rewind, but you mentioned this would be broken for 32-bit devices due to the use of the 'boundary'. I really have no idea how we can detect a rewind in this configuration, so if you are asking to detect when the appl_ptr is modified through some other means (which I didn't get) we will have the same problem, won't we?
see the initial thread here:
https://lore.kernel.org/alsa-devel/de5e91c6-5f0e-9866-a1c2-0943b4342359@linu...
On Tue, 05 Oct 2021 15:10:40 +0200, Pierre-Louis Bossart wrote:
On 10/5/21 1:59 AM, Takashi Iwai wrote:
On Mon, 04 Oct 2021 18:24:21 +0200, Pierre-Louis Bossart wrote:
When the hardware can only deal with a monotonically increasing appl_ptr, this flag can be set. In case the application requests a rewind, snd_pcm_rewind() will not return an error code but signal that the appl_ptr was not modified.
This modification itself is fine, but I guess that application may still move the appl_ptr directly via SNDRV_PCM_IOCTL_SYNC_PTR ioctl. We need to verify the backward move there, I suppose?
Sorry Takashi, I wasn't able to fully follow your question.
In the previous version, I had an explicit check to see if the appl_ptr was modified by a rewind, but you mentioned this would be broken for 32-bit devices due to the use of the 'boundary'. I really have no idea how we can detect a rewind in this configuration, so if you are asking to detect when the appl_ptr is modified through some other means (which I didn't get) we will have the same problem, won't we?
Which same problem are you referring to?
What I suggested here is that there is still a way to modify the appl_ptr from user-space even if you plug the way by disabling the status/control mmap and disabling the rewind ioctl. You have to cover the sync_ptr ioctl call path as well, and it'd need a backward check.
see the initial thread here:
https://lore.kernel.org/alsa-devel/de5e91c6-5f0e-9866-a1c2-0943b4342359@linu...
And, what I meant in the previous thread was that the check in the given patch wasn't "enough", i.e. it needs more careful checks considering the boundary crossing. That is, you can't simply compare appl_ptr vs old_appl_ptr as a single condition for the backward move.
For example, check snd_pcm_playback_avail() and co. That contains a couple of more condition checks and corrections due to the possible boundary crossing. (Here, runtime->boundary may differ depending on 32 or 64bit context.)
The actual implementation of the backward move check would be slightly different from those, but I hope you get my idea.
Takashi
And, what I meant in the previous thread was that the check in the given patch wasn't "enough", i.e. it needs more careful checks considering the boundary crossing. That is, you can't simply compare appl_ptr vs old_appl_ptr as a single condition for the backward move.
Indeed, that's why I tried to avoid any checks on pointers :-)
For example, check snd_pcm_playback_avail() and co. That contains a couple of more condition checks and corrections due to the possible boundary crossing. (Here, runtime->boundary may differ depending on 32 or 64bit context.)
The actual implementation of the backward move check would be slightly different from those, but I hope you get my idea.
I think I do but not sure how to precisely deal with the boundary wrap-around.
The only suggestion I have at this point would be to compare the 'avail' space before and after the appl_ptr changes in pcm_lib_apply_appl_ptr(). If the 'avail' space grows as a result of user-space changes, that indicates a rewind (both for capture and playback), doesn't it?
A tentative solution is shared here: https://github.com/thesofproject/linux/pull/3207
On Tue, 12 Oct 2021 02:19:16 +0200, Pierre-Louis Bossart wrote:
For example, check snd_pcm_playback_avail() and co. That contains a couple of more condition checks and corrections due to the possible boundary crossing. (Here, runtime->boundary may differ depending on 32 or 64bit context.)
The actual implementation of the backward move check would be slightly different from those, but I hope you get my idea.
I think I do but not sure how to precisely deal with the boundary wrap-around.
The only suggestion I have at this point would be to compare the 'avail' space before and after the appl_ptr changes in pcm_lib_apply_appl_ptr(). If the 'avail' space grows as a result of user-space changes, that indicates a rewind (both for capture and playback), doesn't it?
There are a few different ways, and a simple one would be to treat as a rewind if the change isn't 0..buffer_size. e.g.
snd_pcm_sframes_t diff = new_ptr - old_ptr;
if (diff >= 0) { if (diff > buffer_size) return REWIND; } else { if (boundary + diff > buffer_size) return REWIND; } return OK;
Or, if a rewind is defined to be -buffer_size..-1, it'd be like:
snd_pcm_sframes_t diff = new_ptr - old_ptr;
if (diff >= 0) { if (boundary - diff <= buffer_size) return REWIND; } else { if (-diff <= buffer_size) return REWIND; } return OK;
In either way, the new_ptr has to be validated beforehand that it's within 0..boundary-1. (old_ptr is assumed to be valid.)
And don't miss that diff is a signed value, so it must be snd_pcm_sframes_t, not *_uframes_t.
Takashi
For example, check snd_pcm_playback_avail() and co. That contains a couple of more condition checks and corrections due to the possible boundary crossing. (Here, runtime->boundary may differ depending on 32 or 64bit context.)
The actual implementation of the backward move check would be slightly different from those, but I hope you get my idea.
I think I do but not sure how to precisely deal with the boundary wrap-around.
The only suggestion I have at this point would be to compare the 'avail' space before and after the appl_ptr changes in pcm_lib_apply_appl_ptr(). If the 'avail' space grows as a result of user-space changes, that indicates a rewind (both for capture and playback), doesn't it?
There are a few different ways, and a simple one would be to treat as a rewind if the change isn't 0..buffer_size. e.g.
snd_pcm_sframes_t diff = new_ptr - old_ptr;
if (diff >= 0) { if (diff > buffer_size) return REWIND; } else { if (boundary + diff > buffer_size) return REWIND; } return OK;
Or, if a rewind is defined to be -buffer_size..-1, it'd be like:
snd_pcm_sframes_t diff = new_ptr - old_ptr;
if (diff >= 0) { if (boundary - diff <= buffer_size) return REWIND; } else { if (-diff <= buffer_size) return REWIND; } return OK;
ok, I'll trust your math :-)
In either way, the new_ptr has to be validated beforehand that it's within 0..boundary-1. (old_ptr is assumed to be valid.)
In the 3 of the calls to pcm_lib_apply_appl_ptr(), the check is done already prior to calling that function if (appl_ptr >= runtime->boundary) appl_ptr -= runtime->boundary; err = pcm_lib_apply_appl_ptr(substream, appl_ptr);
it's rather unclear to me why the same check is not done for sync_ptr, e.g.
if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, sync_ptr.c.control.appl_ptr);
if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, scontrol.appl_ptr);
Should I add a check there, or add a check inside of pcm_lib_apply_appl_ptr() which would be a duplicate in the majority of cases?
On Tue, 12 Oct 2021 17:15:56 +0200, Pierre-Louis Bossart wrote:
In either way, the new_ptr has to be validated beforehand that it's within 0..boundary-1. (old_ptr is assumed to be valid.)
In the 3 of the calls to pcm_lib_apply_appl_ptr(), the check is done already prior to calling that function if (appl_ptr >= runtime->boundary) appl_ptr -= runtime->boundary; err = pcm_lib_apply_appl_ptr(substream, appl_ptr);
it's rather unclear to me why the same check is not done for sync_ptr, e.g.
if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, sync_ptr.c.control.appl_ptr);
if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, scontrol.appl_ptr);
Should I add a check there, or add a check inside of pcm_lib_apply_appl_ptr() which would be a duplicate in the majority of cases?
I guess adding in pcm_lib_appl_appl_ptr() would be easier and safer. There is even one more place that is calling pcm_lib_apply_appl_ptr() in the very latest commit (a fix for a buggy 32bit compat ioctl).
thanks,
Takashi
On 10/12/21 10:27 AM, Takashi Iwai wrote:
On Tue, 12 Oct 2021 17:15:56 +0200, Pierre-Louis Bossart wrote:
In either way, the new_ptr has to be validated beforehand that it's within 0..boundary-1. (old_ptr is assumed to be valid.)
In the 3 of the calls to pcm_lib_apply_appl_ptr(), the check is done already prior to calling that function if (appl_ptr >= runtime->boundary) appl_ptr -= runtime->boundary; err = pcm_lib_apply_appl_ptr(substream, appl_ptr);
it's rather unclear to me why the same check is not done for sync_ptr, e.g.
if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, sync_ptr.c.control.appl_ptr);
if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, scontrol.appl_ptr);
Should I add a check there, or add a check inside of pcm_lib_apply_appl_ptr() which would be a duplicate in the majority of cases?
I guess adding in pcm_lib_appl_appl_ptr() would be easier and safer. There is even one more place that is calling pcm_lib_apply_appl_ptr() in the very latest commit (a fix for a buggy 32bit compat ioctl).
ok, here's the code I'll start testing. Thanks a lot Takashi for your help.
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index a144a3f68e9e..e839459916ca 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -2127,11 +2127,30 @@ int pcm_lib_apply_appl_ptr(struct snd_pcm_substream *substream, { struct snd_pcm_runtime *runtime = substream->runtime; snd_pcm_uframes_t old_appl_ptr = runtime->control->appl_ptr; + snd_pcm_sframes_t diff; int ret;
if (old_appl_ptr == appl_ptr) return 0;
+ /* + * check if a rewind is requested by the application, after + * verifying the new appl_ptr is in the 0..boundary range + */ + if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) { + if (appl_ptr >= runtime->boundary) + appl_ptr -= runtime->boundary; + + diff = appl_ptr - old_appl_ptr; + if (diff >= 0) { + if (diff > runtime->buffer_size) + return 0; + } else { + if (runtime->boundary + diff > runtime->buffer_size) + return 0; + } + } + runtime->control->appl_ptr = appl_ptr; if (substream->ops->ack) { ret = substream->ops->ack(substream);
On Tue, 12 Oct 2021 18:41:19 +0200, Pierre-Louis Bossart wrote:
On 10/12/21 10:27 AM, Takashi Iwai wrote:
On Tue, 12 Oct 2021 17:15:56 +0200, Pierre-Louis Bossart wrote:
In either way, the new_ptr has to be validated beforehand that it's within 0..boundary-1. (old_ptr is assumed to be valid.)
In the 3 of the calls to pcm_lib_apply_appl_ptr(), the check is done already prior to calling that function if (appl_ptr >= runtime->boundary) appl_ptr -= runtime->boundary; err = pcm_lib_apply_appl_ptr(substream, appl_ptr);
it's rather unclear to me why the same check is not done for sync_ptr, e.g.
if (!(sync_ptr.flags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, sync_ptr.c.control.appl_ptr);
if (!(sflags & SNDRV_PCM_SYNC_PTR_APPL)) { err = pcm_lib_apply_appl_ptr(substream, scontrol.appl_ptr);
Should I add a check there, or add a check inside of pcm_lib_apply_appl_ptr() which would be a duplicate in the majority of cases?
I guess adding in pcm_lib_appl_appl_ptr() would be easier and safer. There is even one more place that is calling pcm_lib_apply_appl_ptr() in the very latest commit (a fix for a buggy 32bit compat ioctl).
ok, here's the code I'll start testing. Thanks a lot Takashi for your help.
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index a144a3f68e9e..e839459916ca 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -2127,11 +2127,30 @@ int pcm_lib_apply_appl_ptr(struct snd_pcm_substream *substream, { struct snd_pcm_runtime *runtime = substream->runtime; snd_pcm_uframes_t old_appl_ptr = runtime->control->appl_ptr;
snd_pcm_sframes_t diff; int ret; if (old_appl_ptr == appl_ptr) return 0;/** check if a rewind is requested by the application, after* verifying the new appl_ptr is in the 0..boundary range*/if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) {if (appl_ptr >= runtime->boundary)appl_ptr -= runtime->boundary;
The boundary check can (or should) be done unconditionally. It was too naive to assume a sane appl_ptr passed always. And, it can rather return an error. So,
if (appl_ptr >= runtime->boundary) return -EINVAL;
/* check if a rewind is requested by the application */ if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) { diff = appl_ptr - old_appl_ptr; ....
if (diff >= 0) {if (diff > runtime->buffer_size)return 0;} else {if (runtime->boundary + diff > runtime->buffer_size)return 0;
I'm not sure whether we should return 0 here. In snd_pcm_rewind() it returns 0 due to application breakage, though.
thanks,
Takashi
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index a144a3f68e9e..e839459916ca 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -2127,11 +2127,30 @@ int pcm_lib_apply_appl_ptr(struct snd_pcm_substream *substream, { struct snd_pcm_runtime *runtime = substream->runtime; snd_pcm_uframes_t old_appl_ptr = runtime->control->appl_ptr;
snd_pcm_sframes_t diff; int ret; if (old_appl_ptr == appl_ptr) return 0;/** check if a rewind is requested by the application, after* verifying the new appl_ptr is in the 0..boundary range*/if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) {if (appl_ptr >= runtime->boundary)appl_ptr -= runtime->boundary;The boundary check can (or should) be done unconditionally. It was too naive to assume a sane appl_ptr passed always. And, it can rather return an error. So,
if (appl_ptr >= runtime->boundary) return -EINVAL;
ok, but that would be a separate patch then since it impacts all users, even without the NO_REWINDS.
/* check if a rewind is requested by the application */ if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) { diff = appl_ptr - old_appl_ptr; ....
if (diff >= 0) {if (diff > runtime->buffer_size)return 0;} else {if (runtime->boundary + diff > runtime->buffer_size)return 0;I'm not sure whether we should return 0 here. In snd_pcm_rewind() it returns 0 due to application breakage, though.
We could return -EINVAL indeed, that would keep the work-around in place for PulseAudio. Even for other uses, it's not so bad: the selection of NO_REWINDS is an opt-in, and if a rewind still occurs a big fail would help detect a configuration issue.
On Tue, 12 Oct 2021 20:02:07 +0200, Pierre-Louis Bossart wrote:
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index a144a3f68e9e..e839459916ca 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -2127,11 +2127,30 @@ int pcm_lib_apply_appl_ptr(struct snd_pcm_substream *substream, { struct snd_pcm_runtime *runtime = substream->runtime; snd_pcm_uframes_t old_appl_ptr = runtime->control->appl_ptr;
snd_pcm_sframes_t diff; int ret; if (old_appl_ptr == appl_ptr) return 0;/** check if a rewind is requested by the application, after* verifying the new appl_ptr is in the 0..boundary range*/if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) {if (appl_ptr >= runtime->boundary)appl_ptr -= runtime->boundary;The boundary check can (or should) be done unconditionally. It was too naive to assume a sane appl_ptr passed always. And, it can rather return an error. So,
if (appl_ptr >= runtime->boundary) return -EINVAL;
ok, but that would be a separate patch then since it impacts all users, even without the NO_REWINDS.
Makes sense.
/* check if a rewind is requested by the application */ if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) { diff = appl_ptr - old_appl_ptr; ....
if (diff >= 0) {if (diff > runtime->buffer_size)return 0;} else {if (runtime->boundary + diff > runtime->buffer_size)return 0;I'm not sure whether we should return 0 here. In snd_pcm_rewind() it returns 0 due to application breakage, though.
We could return -EINVAL indeed, that would keep the work-around in place for PulseAudio. Even for other uses, it's not so bad: the selection of NO_REWINDS is an opt-in, and if a rewind still occurs a big fail would help detect a configuration issue.
Yeah, that was my gut feeling ,too.
Takashi
From: Ranjani Sridharan ranjani.sridharan@linux.intel.com
Add the indirections required at the core level for platform-specific operations on ack.
Note that on errors in the .ack the ALSA core will restore the previous appl_ptr.
Reviewed-by: Péter Ujfalusi peter.ujfalusi@linux.intel.com Reviewed-by: Kai Vehmanen kai.vehmanen@linux.intel.com Signed-off-by: Ranjani Sridharan ranjani.sridharan@linux.intel.com Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- sound/soc/sof/ops.h | 10 ++++++++++ sound/soc/sof/pcm.c | 9 +++++++++ sound/soc/sof/sof-priv.h | 3 +++ 3 files changed, 22 insertions(+)
diff --git a/sound/soc/sof/ops.h b/sound/soc/sof/ops.h index a93aa5b943b2..ca63efce493b 100644 --- a/sound/soc/sof/ops.h +++ b/sound/soc/sof/ops.h @@ -449,6 +449,16 @@ snd_sof_pcm_platform_pointer(struct snd_sof_dev *sdev, return 0; }
+/* pcm ack */ +static inline int snd_sof_pcm_platform_ack(struct snd_sof_dev *sdev, + struct snd_pcm_substream *substream) +{ + if (sof_ops(sdev) && sof_ops(sdev)->pcm_ack) + return sof_ops(sdev)->pcm_ack(sdev, substream); + + return 0; +} + #if IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_PROBES) static inline int snd_sof_probe_compr_assign(struct snd_sof_dev *sdev, diff --git a/sound/soc/sof/pcm.c b/sound/soc/sof/pcm.c index 374df2dfa816..172a2737eaac 100644 --- a/sound/soc/sof/pcm.c +++ b/sound/soc/sof/pcm.c @@ -864,6 +864,14 @@ static void sof_pcm_remove(struct snd_soc_component *component) snd_soc_tplg_component_remove(component); }
+static int sof_pcm_ack(struct snd_soc_component *component, + struct snd_pcm_substream *substream) +{ + struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(component); + + return snd_sof_pcm_platform_ack(sdev, substream); +} + void snd_sof_new_platform_drv(struct snd_sof_dev *sdev) { struct snd_soc_component_driver *pd = &sdev->plat_drv; @@ -882,6 +890,7 @@ void snd_sof_new_platform_drv(struct snd_sof_dev *sdev) pd->hw_free = sof_pcm_hw_free; pd->trigger = sof_pcm_trigger; pd->pointer = sof_pcm_pointer; + pd->ack = sof_pcm_ack;
#if IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_PROBES) pd->compress_ops = &sof_probe_compressed_ops; diff --git a/sound/soc/sof/sof-priv.h b/sound/soc/sof/sof-priv.h index 1289e2efeb62..753b6ef27f40 100644 --- a/sound/soc/sof/sof-priv.h +++ b/sound/soc/sof/sof-priv.h @@ -189,6 +189,9 @@ struct snd_sof_dsp_ops { snd_pcm_uframes_t (*pcm_pointer)(struct snd_sof_dev *sdev, struct snd_pcm_substream *substream); /* optional */
+ /* pcm ack */ + int (*pcm_ack)(struct snd_sof_dev *sdev, struct snd_pcm_substream *substream); /* optional */ + #if IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_PROBES) /* Except for probe_pointer, all probe ops are mandatory */ int (*probe_assign)(struct snd_sof_dev *sdev,
From: Ranjani Sridharan ranjani.sridharan@linux.intel.com
When we disable rewinds, then the .ack can be used to program SPIB with the application pointer, which allows the HDaudio DMA to save power by opportunistically bursting data transfers when the path to memory is enabled (and conversely to shut it down when there are no transfer requests).
The SPIB register can only be programmed with incremental values with wrap-around after the DMA RUN bits are set. For simplicity, we set the INFO_NO_REWINDS flag in the .open callback when we already need to program the SNDRV_PCM_INFO_EXPLICIT_SYNC flag.
Rewinds are not used by many applications. One notable application using rewinds is PulseAudio. Practical experiments with Ubuntu/PulseAudio default settings did not show any audible issues, but the user may hear volume changes and notification with a delay, depending on the size of the ring buffer and latency constraints.
The choice of disabling rewinds is exposed as a kernel parameter and not a Kconfig option to avoid any undesirable side-effects.
Reviewed-by: Péter Ujfalusi peter.ujfalusi@linux.intel.com Reviewed-by: Kai Vehmanen kai.vehmanen@linux.intel.com Reviewed-by: Ranjani Sridharan ranjani.sridharan@linux.intel.com Co-developed-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com Signed-off-by: Ranjani Sridharan ranjani.sridharan@linux.intel.com --- sound/soc/sof/intel/apl.c | 1 + sound/soc/sof/intel/cnl.c | 1 + sound/soc/sof/intel/hda-pcm.c | 41 ++++++++++++++++++++++++++++++-- sound/soc/sof/intel/hda-stream.c | 2 ++ sound/soc/sof/intel/hda.h | 1 + sound/soc/sof/intel/tgl.c | 1 + 6 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/sound/soc/sof/intel/apl.c b/sound/soc/sof/intel/apl.c index e6a1f6532547..cb457f46fca5 100644 --- a/sound/soc/sof/intel/apl.c +++ b/sound/soc/sof/intel/apl.c @@ -74,6 +74,7 @@ const struct snd_sof_dsp_ops sof_apl_ops = { .pcm_hw_free = hda_dsp_stream_hw_free, .pcm_trigger = hda_dsp_pcm_trigger, .pcm_pointer = hda_dsp_pcm_pointer, + .pcm_ack = hda_dsp_pcm_ack,
#if IS_ENABLED(CONFIG_SND_SOC_SOF_HDA_PROBES) /* probe callbacks */ diff --git a/sound/soc/sof/intel/cnl.c b/sound/soc/sof/intel/cnl.c index 430a268e6b26..1c619f3241ac 100644 --- a/sound/soc/sof/intel/cnl.c +++ b/sound/soc/sof/intel/cnl.c @@ -279,6 +279,7 @@ const struct snd_sof_dsp_ops sof_cnl_ops = { .pcm_hw_free = hda_dsp_stream_hw_free, .pcm_trigger = hda_dsp_pcm_trigger, .pcm_pointer = hda_dsp_pcm_pointer, + .pcm_ack = hda_dsp_pcm_ack,
#if IS_ENABLED(CONFIG_SND_SOC_SOF_HDA_PROBES) /* probe callbacks */ diff --git a/sound/soc/sof/intel/hda-pcm.c b/sound/soc/sof/intel/hda-pcm.c index cc8ddef37f37..875350283eac 100644 --- a/sound/soc/sof/intel/hda-pcm.c +++ b/sound/soc/sof/intel/hda-pcm.c @@ -32,6 +32,10 @@ static bool hda_always_enable_dmi_l1; module_param_named(always_enable_dmi_l1, hda_always_enable_dmi_l1, bool, 0444); MODULE_PARM_DESC(always_enable_dmi_l1, "SOF HDA always enable DMI l1");
+static bool hda_disable_rewinds = IS_ENABLED(CONFIG_SND_SOC_SOF_HDA_DISABLE_REWINDS); +module_param_named(disable_rewinds, hda_disable_rewinds, bool, 0444); +MODULE_PARM_DESC(disable_rewinds, "SOF HDA disable rewinds"); + u32 hda_dsp_get_mult_div(struct snd_sof_dev *sdev, int rate) { switch (rate) { @@ -120,8 +124,11 @@ int hda_dsp_pcm_hw_params(struct snd_sof_dev *sdev, return ret; }
- /* disable SPIB, to enable buffer wrap for stream */ - hda_dsp_stream_spib_config(sdev, stream, HDA_DSP_SPIB_DISABLE, 0); + /* enable SPIB when rewinds are disabled */ + if (hda_disable_rewinds) + hda_dsp_stream_spib_config(sdev, stream, HDA_DSP_SPIB_ENABLE, 0); + else + hda_dsp_stream_spib_config(sdev, stream, HDA_DSP_SPIB_DISABLE, 0);
/* update no_stream_position flag for ipc params */ if (hda && hda->no_ipc_position) { @@ -140,6 +147,29 @@ int hda_dsp_pcm_hw_params(struct snd_sof_dev *sdev, return 0; }
+/* update SPIB register with appl position */ +int hda_dsp_pcm_ack(struct snd_sof_dev *sdev, struct snd_pcm_substream *substream) +{ + struct hdac_stream *hstream = substream->runtime->private_data; + struct hdac_ext_stream *stream = stream_to_hdac_ext_stream(hstream); + struct snd_pcm_runtime *runtime = substream->runtime; + ssize_t appl_pos, buf_size; + u32 spib; + + appl_pos = frames_to_bytes(runtime, runtime->control->appl_ptr); + buf_size = frames_to_bytes(runtime, runtime->buffer_size); + + spib = appl_pos % buf_size; + + /* Allowable value for SPIB is 1 byte to max buffer size */ + if (!spib) + spib = buf_size; + + sof_io_write(sdev, stream->spib_addr, spib); + + return 0; +} + int hda_dsp_pcm_trigger(struct snd_sof_dev *sdev, struct snd_pcm_substream *substream, int cmd) { @@ -234,6 +264,13 @@ int hda_dsp_pcm_open(struct snd_sof_dev *sdev, return -EINVAL; }
+ /* + * if we want the .ack to work, we need to prevent the status and + * control from being mapped + */ + if (hda_disable_rewinds) + runtime->hw.info |= SNDRV_PCM_INFO_NO_REWINDS | SNDRV_PCM_INFO_EXPLICIT_SYNC; + /* * All playback streams are DMI L1 capable, capture streams need * pause push/release to be disabled diff --git a/sound/soc/sof/intel/hda-stream.c b/sound/soc/sof/intel/hda-stream.c index 1d845c2cbc33..b6f037815344 100644 --- a/sound/soc/sof/intel/hda-stream.c +++ b/sound/soc/sof/intel/hda-stream.c @@ -655,6 +655,8 @@ int hda_dsp_stream_hw_free(struct snd_sof_dev *sdev, SOF_HDA_REG_PP_PPCTL, mask, 0); spin_unlock_irq(&bus->reg_lock);
+ hda_dsp_stream_spib_config(sdev, link_dev, HDA_DSP_SPIB_DISABLE, 0); + stream->substream = NULL;
return 0; diff --git a/sound/soc/sof/intel/hda.h b/sound/soc/sof/intel/hda.h index 1195018a1f4f..6829d36fbfe9 100644 --- a/sound/soc/sof/intel/hda.h +++ b/sound/soc/sof/intel/hda.h @@ -533,6 +533,7 @@ int hda_dsp_pcm_trigger(struct snd_sof_dev *sdev, struct snd_pcm_substream *substream, int cmd); snd_pcm_uframes_t hda_dsp_pcm_pointer(struct snd_sof_dev *sdev, struct snd_pcm_substream *substream); +int hda_dsp_pcm_ack(struct snd_sof_dev *sdev, struct snd_pcm_substream *substream);
/* * DSP Stream Operations. diff --git a/sound/soc/sof/intel/tgl.c b/sound/soc/sof/intel/tgl.c index 664a11aaada2..88491b97fde7 100644 --- a/sound/soc/sof/intel/tgl.c +++ b/sound/soc/sof/intel/tgl.c @@ -69,6 +69,7 @@ const struct snd_sof_dsp_ops sof_tgl_ops = { .pcm_hw_free = hda_dsp_stream_hw_free, .pcm_trigger = hda_dsp_pcm_trigger, .pcm_pointer = hda_dsp_pcm_pointer, + .pcm_ack = hda_dsp_pcm_ack,
#if IS_ENABLED(CONFIG_SND_SOC_SOF_HDA_PROBES) /* probe callbacks */
participants (2)
-
Pierre-Louis Bossart -
Takashi Iwai