Reuse the dma channel if available in Back-End
Shengjiu Wang (3):
ASoC: soc-card: export snd_soc_lookup_component_nolocked
ASoC: dmaengine_pcm: export soc_component_to_pcm
ASoC: fsl_asrc_dma: Reuse the dma channel if available in Back-End
changes in v2:
- update according to Mark's comments and split the patch
include/sound/dmaengine_pcm.h | 11 ++++++
include/sound/soc.h | 2 ++
sound/soc/fsl/fsl_asrc_common.h | 2 ++
sound/soc/fsl/fsl_asrc_dma.c | 52 ++++++++++++++++++++-------
sound/soc/soc-core.c | 3 +-
sound/soc/soc-generic-dmaengine-pcm.c | 12 -------
6 files changed, 57 insertions(+), 25 deletions(-)
--
2.21.0
snd_soc_lookup_component_nolocked can be used for the DPCM case
that Front-End needs to get the unused platform component but
added by Back-End cpu dai driver.
If the component is gotten, then we can get the dma chan created
by Back-End component and reused it in Front-End.
Signed-off-by: Shengjiu Wang <[email protected]>
---
include/sound/soc.h | 2 ++
sound/soc/soc-core.c | 3 ++-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/sound/soc.h b/include/sound/soc.h
index 74868436ac79..565612a8d690 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -444,6 +444,8 @@ int devm_snd_soc_register_component(struct device *dev,
const struct snd_soc_component_driver *component_driver,
struct snd_soc_dai_driver *dai_drv, int num_dai);
void snd_soc_unregister_component(struct device *dev);
+struct snd_soc_component *snd_soc_lookup_component_nolocked(struct device *dev,
+ const char *driver_name);
struct snd_soc_component *snd_soc_lookup_component(struct device *dev,
const char *driver_name);
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index b07eca2c6ccc..d4c73e86d058 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -310,7 +310,7 @@ struct snd_soc_component *snd_soc_rtdcom_lookup(struct snd_soc_pcm_runtime *rtd,
}
EXPORT_SYMBOL_GPL(snd_soc_rtdcom_lookup);
-static struct snd_soc_component
+struct snd_soc_component
*snd_soc_lookup_component_nolocked(struct device *dev, const char *driver_name)
{
struct snd_soc_component *component;
@@ -329,6 +329,7 @@ static struct snd_soc_component
return found_component;
}
+EXPORT_SYMBOL_GPL(snd_soc_lookup_component_nolocked);
struct snd_soc_component *snd_soc_lookup_component(struct device *dev,
const char *driver_name)
--
2.21.0
In DPCM case, Front-End needs to get the dma chan which has
been requested by Back-End and reuse it.
Signed-off-by: Shengjiu Wang <[email protected]>
---
include/sound/dmaengine_pcm.h | 11 +++++++++++
sound/soc/soc-generic-dmaengine-pcm.c | 12 ------------
2 files changed, 11 insertions(+), 12 deletions(-)
diff --git a/include/sound/dmaengine_pcm.h b/include/sound/dmaengine_pcm.h
index b65220685920..8c5e38180fb0 100644
--- a/include/sound/dmaengine_pcm.h
+++ b/include/sound/dmaengine_pcm.h
@@ -161,4 +161,15 @@ int snd_dmaengine_pcm_prepare_slave_config(struct snd_pcm_substream *substream,
#define SND_DMAENGINE_PCM_DRV_NAME "snd_dmaengine_pcm"
+struct dmaengine_pcm {
+ struct dma_chan *chan[SNDRV_PCM_STREAM_LAST + 1];
+ const struct snd_dmaengine_pcm_config *config;
+ struct snd_soc_component component;
+ unsigned int flags;
+};
+
+static inline struct dmaengine_pcm *soc_component_to_pcm(struct snd_soc_component *p)
+{
+ return container_of(p, struct dmaengine_pcm, component);
+}
#endif
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
index f728309a0833..80a4e71f2d95 100644
--- a/sound/soc/soc-generic-dmaengine-pcm.c
+++ b/sound/soc/soc-generic-dmaengine-pcm.c
@@ -21,18 +21,6 @@
*/
#define SND_DMAENGINE_PCM_FLAG_NO_RESIDUE BIT(31)
-struct dmaengine_pcm {
- struct dma_chan *chan[SNDRV_PCM_STREAM_LAST + 1];
- const struct snd_dmaengine_pcm_config *config;
- struct snd_soc_component component;
- unsigned int flags;
-};
-
-static struct dmaengine_pcm *soc_component_to_pcm(struct snd_soc_component *p)
-{
- return container_of(p, struct dmaengine_pcm, component);
-}
-
static struct device *dmaengine_dma_dev(struct dmaengine_pcm *pcm,
struct snd_pcm_substream *substream)
{
--
2.21.0
The dma channel has been requested by Back-End cpu dai driver already.
If fsl_asrc_dma requests dma chan with same dma:tx symlink, then
there will be below warning with SDMA.
[ 48.174236] fsl-esai-dai 2024000.esai: Cannot create DMA dma:tx symlink
or with EDMA the request operation will fail for EDMA channel
can only be requested once.
So If we can reuse the dma channel of Back-End, then the issue can be
fixed.
In order to get the dma channel which is already requested in Back-End.
we use the exported two functions (snd_soc_lookup_component_nolocked
and soc_component_to_pcm). If we can get the dma channel, then reuse it,
if can't, then request a new one.
Signed-off-by: Shengjiu Wang <[email protected]>
---
sound/soc/fsl/fsl_asrc_common.h | 2 ++
sound/soc/fsl/fsl_asrc_dma.c | 52 +++++++++++++++++++++++++--------
2 files changed, 42 insertions(+), 12 deletions(-)
diff --git a/sound/soc/fsl/fsl_asrc_common.h b/sound/soc/fsl/fsl_asrc_common.h
index 77665b15c8db..09512bc79b80 100644
--- a/sound/soc/fsl/fsl_asrc_common.h
+++ b/sound/soc/fsl/fsl_asrc_common.h
@@ -32,6 +32,7 @@ enum asrc_pair_index {
* @dma_chan: inputer and output DMA channels
* @dma_data: private dma data
* @pos: hardware pointer position
+ * @req_dma_chan_dev_to_dev: flag for release dev_to_dev chan
* @private: pair private area
*/
struct fsl_asrc_pair {
@@ -45,6 +46,7 @@ struct fsl_asrc_pair {
struct dma_chan *dma_chan[2];
struct imx_dma_data dma_data;
unsigned int pos;
+ bool req_dma_chan_dev_to_dev;
void *private;
};
diff --git a/sound/soc/fsl/fsl_asrc_dma.c b/sound/soc/fsl/fsl_asrc_dma.c
index d6a3fc5f87e5..5ecb77d466d3 100644
--- a/sound/soc/fsl/fsl_asrc_dma.c
+++ b/sound/soc/fsl/fsl_asrc_dma.c
@@ -133,6 +133,7 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
struct snd_dmaengine_dai_dma_data *dma_params_fe = NULL;
struct snd_dmaengine_dai_dma_data *dma_params_be = NULL;
+ struct dma_chan *tmp_chan = NULL, *tmp_chan_new = NULL;
struct snd_pcm_runtime *runtime = substream->runtime;
struct fsl_asrc_pair *pair = runtime->private_data;
struct fsl_asrc *asrc = pair->asrc;
@@ -142,7 +143,6 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
int stream = substream->stream;
struct imx_dma_data *tmp_data;
struct snd_soc_dpcm *dpcm;
- struct dma_chan *tmp_chan;
struct device *dev_be;
u8 dir = tx ? OUT : IN;
dma_cap_mask_t mask;
@@ -152,6 +152,7 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
for_each_dpcm_be(rtd, stream, dpcm) {
struct snd_soc_pcm_runtime *be = dpcm->be;
struct snd_pcm_substream *substream_be;
+ struct snd_soc_component *component_be;
struct snd_soc_dai *dai = asoc_rtd_to_cpu(be, 0);
if (dpcm->fe != rtd)
@@ -160,6 +161,9 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
substream_be = snd_soc_dpcm_get_substream(be, stream);
dma_params_be = snd_soc_dai_get_dma_data(dai, substream_be);
dev_be = dai->dev;
+ component_be = snd_soc_lookup_component_nolocked(dev_be, SND_DMAENGINE_PCM_DRV_NAME);
+ if (component_be)
+ tmp_chan = soc_component_to_pcm(component_be)->chan[substream->stream];
break;
}
@@ -205,10 +209,14 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
*/
if (!asrc->use_edma) {
/* Get DMA request of Back-End */
- tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
+ if (!tmp_chan) {
+ tmp_chan_new = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
+ tmp_chan = tmp_chan_new;
+ }
tmp_data = tmp_chan->private;
pair->dma_data.dma_request = tmp_data->dma_request;
- dma_release_channel(tmp_chan);
+ if (tmp_chan_new)
+ dma_release_channel(tmp_chan_new);
/* Get DMA request of Front-End */
tmp_chan = asrc->get_dma_channel(pair, dir);
@@ -220,9 +228,26 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
pair->dma_chan[dir] =
dma_request_channel(mask, filter, &pair->dma_data);
+ pair->req_dma_chan_dev_to_dev = true;
} else {
- pair->dma_chan[dir] =
- asrc->get_dma_channel(pair, dir);
+ /*
+ * With EDMA, there is two dma channels can be used for p2p,
+ * one is from ASRC, one is from another peripheral
+ * (ESAI or SAI). Previously we select the dma channel of ASRC,
+ * but find an issue for ideal ratio case, there is no control
+ * for data copy speed, the speed is faster than sample
+ * frequency.
+ *
+ * So we switch to use dma channel of peripheral (ESAI or SAI),
+ * that copy speed of DMA is controlled by data consumption
+ * speed in the peripheral FIFO.
+ */
+ pair->req_dma_chan_dev_to_dev = false;
+ pair->dma_chan[dir] = tmp_chan;
+ if (!pair->dma_chan[dir]) {
+ pair->dma_chan[dir] = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
+ pair->req_dma_chan_dev_to_dev = true;
+ }
}
if (!pair->dma_chan[dir]) {
@@ -261,7 +286,8 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
ret = dmaengine_slave_config(pair->dma_chan[dir], &config_be);
if (ret) {
dev_err(dev, "failed to config DMA channel for Back-End\n");
- dma_release_channel(pair->dma_chan[dir]);
+ if (pair->req_dma_chan_dev_to_dev)
+ dma_release_channel(pair->dma_chan[dir]);
return ret;
}
@@ -273,19 +299,21 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
static int fsl_asrc_dma_hw_free(struct snd_soc_component *component,
struct snd_pcm_substream *substream)
{
+ bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
struct snd_pcm_runtime *runtime = substream->runtime;
struct fsl_asrc_pair *pair = runtime->private_data;
+ u8 dir = tx ? OUT : IN;
snd_pcm_set_runtime_buffer(substream, NULL);
- if (pair->dma_chan[IN])
- dma_release_channel(pair->dma_chan[IN]);
+ if (pair->dma_chan[!dir])
+ dma_release_channel(pair->dma_chan[!dir]);
- if (pair->dma_chan[OUT])
- dma_release_channel(pair->dma_chan[OUT]);
+ if (pair->dma_chan[dir] && pair->req_dma_chan_dev_to_dev)
+ dma_release_channel(pair->dma_chan[dir]);
- pair->dma_chan[IN] = NULL;
- pair->dma_chan[OUT] = NULL;
+ pair->dma_chan[!dir] = NULL;
+ pair->dma_chan[dir] = NULL;
return 0;
}
--
2.21.0
On Wed, Jun 10, 2020 at 06:05:49PM +0800, Shengjiu Wang wrote:
> The dma channel has been requested by Back-End cpu dai driver already.
> If fsl_asrc_dma requests dma chan with same dma:tx symlink, then
> there will be below warning with SDMA.
>
> [ 48.174236] fsl-esai-dai 2024000.esai: Cannot create DMA dma:tx symlink
>
> or with EDMA the request operation will fail for EDMA channel
> can only be requested once.
>
> So If we can reuse the dma channel of Back-End, then the issue can be
> fixed.
>
> In order to get the dma channel which is already requested in Back-End.
> we use the exported two functions (snd_soc_lookup_component_nolocked
> and soc_component_to_pcm). If we can get the dma channel, then reuse it,
> if can't, then request a new one.
>
> Signed-off-by: Shengjiu Wang <[email protected]>
> ---
> sound/soc/fsl/fsl_asrc_common.h | 2 ++
> sound/soc/fsl/fsl_asrc_dma.c | 52 +++++++++++++++++++++++++--------
> 2 files changed, 42 insertions(+), 12 deletions(-)
> diff --git a/sound/soc/fsl/fsl_asrc_common.h b/sound/soc/fsl/fsl_asrc_common.h
> index 77665b15c8db..09512bc79b80 100644
> --- a/sound/soc/fsl/fsl_asrc_common.h
> +++ b/sound/soc/fsl/fsl_asrc_common.h
> @@ -32,6 +32,7 @@ enum asrc_pair_index {
> * @dma_chan: inputer and output DMA channels
> * @dma_data: private dma data
> * @pos: hardware pointer position
> + * @req_dma_chan_dev_to_dev: flag for release dev_to_dev chan
Since we only have dma_request call for back-end only:
+ * @req_dma_chan: flag to release back-end dma chan
> diff --git a/sound/soc/fsl/fsl_asrc_dma.c b/sound/soc/fsl/fsl_asrc_dma.c
> index d6a3fc5f87e5..5ecb77d466d3 100644
> --- a/sound/soc/fsl/fsl_asrc_dma.c
> +++ b/sound/soc/fsl/fsl_asrc_dma.c
> @@ -160,6 +161,9 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> substream_be = snd_soc_dpcm_get_substream(be, stream);
> dma_params_be = snd_soc_dai_get_dma_data(dai, substream_be);
> dev_be = dai->dev;
> + component_be = snd_soc_lookup_component_nolocked(dev_be, SND_DMAENGINE_PCM_DRV_NAME);
> + if (component_be)
> + tmp_chan = soc_component_to_pcm(component_be)->chan[substream->stream];
Should we use substream_be->stream or just substream->stream?
And would be better to add these lines right before we really use
tmp_chan because there's still some distance till it reaches that
point. And would be better to have a line of comments too.
> @@ -205,10 +209,14 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> */
> if (!asrc->use_edma) {
> /* Get DMA request of Back-End */
> - tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
> + if (!tmp_chan) {
> + tmp_chan_new = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
> + tmp_chan = tmp_chan_new;
This is a bit confusing...though I finally got it :)
So probably better to have a line of comments.
> @@ -220,9 +228,26 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
>
> pair->dma_chan[dir] =
> dma_request_channel(mask, filter, &pair->dma_data);
> + pair->req_dma_chan_dev_to_dev = true;
> } else {
> - pair->dma_chan[dir] =
> - asrc->get_dma_channel(pair, dir);
> + /*
> + * With EDMA, there is two dma channels can be used for p2p,
> + * one is from ASRC, one is from another peripheral
> + * (ESAI or SAI). Previously we select the dma channel of ASRC,
> + * but find an issue for ideal ratio case, there is no control
> + * for data copy speed, the speed is faster than sample
> + * frequency.
> + *
> + * So we switch to use dma channel of peripheral (ESAI or SAI),
> + * that copy speed of DMA is controlled by data consumption
> + * speed in the peripheral FIFO.
> + */
This sounds like a different issue and should be fixed separately?
If you prefer not to, better to move this one to commit log, other
than having a changelog here, in my opinion.
Since it no longer uses get_dma_channel() for EDMA case, we should
update the comments at the top as well.
> + pair->req_dma_chan_dev_to_dev = false;
> + pair->dma_chan[dir] = tmp_chan;
> + if (!pair->dma_chan[dir]) {
> + pair->dma_chan[dir] = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
> + pair->req_dma_chan_dev_to_dev = true;
> + }
> }
Now there are some duplicated lines between these if-else routines, so
combining my previous comments, we can do (sample change, not tested):
@@ -197,18 +199,29 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
dma_cap_set(DMA_SLAVE, mask);
dma_cap_set(DMA_CYCLIC, mask);
+ /*
+ * The Back-End device might have already requested a DMA channel,
+ * so try to reuse it first, and then request a new one upon NULL.
+ */
+ component_be = snd_soc_lookup_component_nolocked(dev_be, SND_DMAENGINE_PCM_DRV_NAME);
+ if (component_be) // should probably error out if !component_be?
+ tmp_chan = be_chan = soc_component_to_pcm(component_be)->chan[substream->stream];
+ if (!tmp_chan)
+ tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
+
/*
* An EDMA DEV_TO_DEV channel is fixed and bound with DMA event of each
* peripheral, unlike SDMA channel that is allocated dynamically. So no
- * need to configure dma_request and dma_request2, but get dma_chan via
- * dma_request_slave_channel directly with dma name of Front-End device
+ * need to configure dma_request and dma_request2, but get dma_chan of
+ * Back-End device directly via dma_request_slave_channel.
*/
if (!asrc->use_edma) {
/* Get DMA request of Back-End */
- tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
tmp_data = tmp_chan->private;
pair->dma_data.dma_request = tmp_data->dma_request;
- dma_release_channel(tmp_chan);
+ /* Do not release tmp_chan if we are reusing the Back-End one */
+ if (!be_chan)
+ dma_release_channel(tmp_chan);
/* Get DMA request of Front-End */
tmp_chan = asrc->get_dma_channel(pair, dir);
@@ -220,9 +233,11 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
pair->dma_chan[dir] =
dma_request_channel(mask, filter, &pair->dma_data);
+ pair->req_dma_chan = true;
} else {
- pair->dma_chan[dir] =
- asrc->get_dma_channel(pair, dir);
+ pair->dma_chan[dir] = tmp_chan;
+ /* Do not flag to release if we are reusing the Back-End one */
+ pair->req_dma_chan = !be_chan;
}
if (!pair->dma_chan[dir]) {
> @@ -273,19 +299,21 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> static int fsl_asrc_dma_hw_free(struct snd_soc_component *component,
> struct snd_pcm_substream *substream)
> {
> + bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
> struct snd_pcm_runtime *runtime = substream->runtime;
> struct fsl_asrc_pair *pair = runtime->private_data;
> + u8 dir = tx ? OUT : IN;
>
> snd_pcm_set_runtime_buffer(substream, NULL);
>
> - if (pair->dma_chan[IN])
> - dma_release_channel(pair->dma_chan[IN]);
> + if (pair->dma_chan[!dir])
> + dma_release_channel(pair->dma_chan[!dir]);
>
> - if (pair->dma_chan[OUT])
> - dma_release_channel(pair->dma_chan[OUT]);
> + if (pair->dma_chan[dir] && pair->req_dma_chan_dev_to_dev)
> + dma_release_channel(pair->dma_chan[dir]);
Why we only apply this to one direction?
On Fri, Jun 12, 2020 at 8:33 AM Nicolin Chen <[email protected]> wrote:
>
> On Wed, Jun 10, 2020 at 06:05:49PM +0800, Shengjiu Wang wrote:
> > The dma channel has been requested by Back-End cpu dai driver already.
> > If fsl_asrc_dma requests dma chan with same dma:tx symlink, then
> > there will be below warning with SDMA.
> >
> > [ 48.174236] fsl-esai-dai 2024000.esai: Cannot create DMA dma:tx symlink
> >
> > or with EDMA the request operation will fail for EDMA channel
> > can only be requested once.
> >
> > So If we can reuse the dma channel of Back-End, then the issue can be
> > fixed.
> >
> > In order to get the dma channel which is already requested in Back-End.
> > we use the exported two functions (snd_soc_lookup_component_nolocked
> > and soc_component_to_pcm). If we can get the dma channel, then reuse it,
> > if can't, then request a new one.
> >
> > Signed-off-by: Shengjiu Wang <[email protected]>
> > ---
> > sound/soc/fsl/fsl_asrc_common.h | 2 ++
> > sound/soc/fsl/fsl_asrc_dma.c | 52 +++++++++++++++++++++++++--------
> > 2 files changed, 42 insertions(+), 12 deletions(-)
>
> > diff --git a/sound/soc/fsl/fsl_asrc_common.h b/sound/soc/fsl/fsl_asrc_common.h
> > index 77665b15c8db..09512bc79b80 100644
> > --- a/sound/soc/fsl/fsl_asrc_common.h
> > +++ b/sound/soc/fsl/fsl_asrc_common.h
> > @@ -32,6 +32,7 @@ enum asrc_pair_index {
> > * @dma_chan: inputer and output DMA channels
> > * @dma_data: private dma data
> > * @pos: hardware pointer position
> > + * @req_dma_chan_dev_to_dev: flag for release dev_to_dev chan
>
> Since we only have dma_request call for back-end only:
> + * @req_dma_chan: flag to release back-end dma chan
I prefer to use the description "flag to release dev_to_dev chan"
because we won't release the dma chan of the back-end. if the chan
is from the back-end, it is owned by the back-end component.
>
> > diff --git a/sound/soc/fsl/fsl_asrc_dma.c b/sound/soc/fsl/fsl_asrc_dma.c
> > index d6a3fc5f87e5..5ecb77d466d3 100644
> > --- a/sound/soc/fsl/fsl_asrc_dma.c
> > +++ b/sound/soc/fsl/fsl_asrc_dma.c
> > @@ -160,6 +161,9 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> > substream_be = snd_soc_dpcm_get_substream(be, stream);
> > dma_params_be = snd_soc_dai_get_dma_data(dai, substream_be);
> > dev_be = dai->dev;
> > + component_be = snd_soc_lookup_component_nolocked(dev_be, SND_DMAENGINE_PCM_DRV_NAME);
> > + if (component_be)
> > + tmp_chan = soc_component_to_pcm(component_be)->chan[substream->stream];
>
> Should we use substream_be->stream or just substream->stream?
substream_be->stream should be better.
>
> And would be better to add these lines right before we really use
> tmp_chan because there's still some distance till it reaches that
> point. And would be better to have a line of comments too.
ok.
>
> > @@ -205,10 +209,14 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> > */
> > if (!asrc->use_edma) {
> > /* Get DMA request of Back-End */
> > - tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
> > + if (!tmp_chan) {
> > + tmp_chan_new = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
> > + tmp_chan = tmp_chan_new;
>
> This is a bit confusing...though I finally got it :)
> So probably better to have a line of comments.
ok.
>
> > @@ -220,9 +228,26 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> >
> > pair->dma_chan[dir] =
> > dma_request_channel(mask, filter, &pair->dma_data);
> > + pair->req_dma_chan_dev_to_dev = true;
> > } else {
> > - pair->dma_chan[dir] =
> > - asrc->get_dma_channel(pair, dir);
> > + /*
> > + * With EDMA, there is two dma channels can be used for p2p,
> > + * one is from ASRC, one is from another peripheral
> > + * (ESAI or SAI). Previously we select the dma channel of ASRC,
> > + * but find an issue for ideal ratio case, there is no control
> > + * for data copy speed, the speed is faster than sample
> > + * frequency.
> > + *
> > + * So we switch to use dma channel of peripheral (ESAI or SAI),
> > + * that copy speed of DMA is controlled by data consumption
> > + * speed in the peripheral FIFO.
> > + */
>
> This sounds like a different issue and should be fixed separately?
> If you prefer not to, better to move this one to commit log, other
> than having a changelog here, in my opinion.
ok, will move it in commit log.
>
> Since it no longer uses get_dma_channel() for EDMA case, we should
> update the comments at the top as well.
>
> > + pair->req_dma_chan_dev_to_dev = false;
> > + pair->dma_chan[dir] = tmp_chan;
> > + if (!pair->dma_chan[dir]) {
> > + pair->dma_chan[dir] = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
> > + pair->req_dma_chan_dev_to_dev = true;
> > + }
> > }
>
> Now there are some duplicated lines between these if-else routines, so
> combining my previous comments, we can do (sample change, not tested):
ok, will try yours.
>
> @@ -197,18 +199,29 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> dma_cap_set(DMA_SLAVE, mask);
> dma_cap_set(DMA_CYCLIC, mask);
>
> + /*
> + * The Back-End device might have already requested a DMA channel,
> + * so try to reuse it first, and then request a new one upon NULL.
> + */
> + component_be = snd_soc_lookup_component_nolocked(dev_be, SND_DMAENGINE_PCM_DRV_NAME);
> + if (component_be) // should probably error out if !component_be?
> + tmp_chan = be_chan = soc_component_to_pcm(component_be)->chan[substream->stream];
> + if (!tmp_chan)
> + tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
> +
> /*
> * An EDMA DEV_TO_DEV channel is fixed and bound with DMA event of each
> * peripheral, unlike SDMA channel that is allocated dynamically. So no
> - * need to configure dma_request and dma_request2, but get dma_chan via
> - * dma_request_slave_channel directly with dma name of Front-End device
> + * need to configure dma_request and dma_request2, but get dma_chan of
> + * Back-End device directly via dma_request_slave_channel.
> */
> if (!asrc->use_edma) {
> /* Get DMA request of Back-End */
> - tmp_chan = dma_request_slave_channel(dev_be, tx ? "tx" : "rx");
> tmp_data = tmp_chan->private;
> pair->dma_data.dma_request = tmp_data->dma_request;
> - dma_release_channel(tmp_chan);
> + /* Do not release tmp_chan if we are reusing the Back-End one */
> + if (!be_chan)
> + dma_release_channel(tmp_chan);
>
> /* Get DMA request of Front-End */
> tmp_chan = asrc->get_dma_channel(pair, dir);
> @@ -220,9 +233,11 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
>
> pair->dma_chan[dir] =
> dma_request_channel(mask, filter, &pair->dma_data);
> + pair->req_dma_chan = true;
> } else {
> - pair->dma_chan[dir] =
> - asrc->get_dma_channel(pair, dir);
> + pair->dma_chan[dir] = tmp_chan;
> + /* Do not flag to release if we are reusing the Back-End one */
> + pair->req_dma_chan = !be_chan;
> }
>
> if (!pair->dma_chan[dir]) {
>
> > @@ -273,19 +299,21 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> > static int fsl_asrc_dma_hw_free(struct snd_soc_component *component,
> > struct snd_pcm_substream *substream)
> > {
> > + bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
> > struct snd_pcm_runtime *runtime = substream->runtime;
> > struct fsl_asrc_pair *pair = runtime->private_data;
> > + u8 dir = tx ? OUT : IN;
> >
> > snd_pcm_set_runtime_buffer(substream, NULL);
> >
> > - if (pair->dma_chan[IN])
> > - dma_release_channel(pair->dma_chan[IN]);
> > + if (pair->dma_chan[!dir])
> > + dma_release_channel(pair->dma_chan[!dir]);
> >
> > - if (pair->dma_chan[OUT])
> > - dma_release_channel(pair->dma_chan[OUT]);
> > + if (pair->dma_chan[dir] && pair->req_dma_chan_dev_to_dev)
> > + dma_release_channel(pair->dma_chan[dir]);
>
> Why we only apply this to one direction?
if the chan is from the back-end, it is owned by the back-end
component, so it should be released by the back-end component,
not here. That's why I added the flag "req_dma_chan".
On Fri, Jun 12, 2020 at 10:17:08AM +0800, Shengjiu Wang wrote:
> > > diff --git a/sound/soc/fsl/fsl_asrc_common.h b/sound/soc/fsl/fsl_asrc_common.h
> > > + * @req_dma_chan_dev_to_dev: flag for release dev_to_dev chan
> >
> > Since we only have dma_request call for back-end only:
> > + * @req_dma_chan: flag to release back-end dma chan
>
> I prefer to use the description "flag to release dev_to_dev chan"
> because we won't release the dma chan of the back-end. if the chan
> is from the back-end, it is owned by the back-end component.
TBH, it just looks too long. But I wouldn't have problem if you
insist so.
> > > @@ -273,19 +299,21 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
> > > static int fsl_asrc_dma_hw_free(struct snd_soc_component *component,
> > > struct snd_pcm_substream *substream)
> > > {
> > > + bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
> > > struct snd_pcm_runtime *runtime = substream->runtime;
> > > struct fsl_asrc_pair *pair = runtime->private_data;
> > > + u8 dir = tx ? OUT : IN;
> > >
> > > snd_pcm_set_runtime_buffer(substream, NULL);
> > >
> > > - if (pair->dma_chan[IN])
> > > - dma_release_channel(pair->dma_chan[IN]);
> > > + if (pair->dma_chan[!dir])
> > > + dma_release_channel(pair->dma_chan[!dir]);
> > >
> > > - if (pair->dma_chan[OUT])
> > > - dma_release_channel(pair->dma_chan[OUT]);
> > > + if (pair->dma_chan[dir] && pair->req_dma_chan_dev_to_dev)
> > > + dma_release_channel(pair->dma_chan[dir]);
> >
> > Why we only apply this to one direction?
>
> if the chan is from the back-end, it is owned by the back-end
> component, so it should be released by the back-end component,
> not here. That's why I added the flag "req_dma_chan".
Ah...I forgot the IN and OUT is for front-end and back-end. The
naming isn't very good indeed. Probably we should add a line of
comments somewhere as a reminder.
Thanks