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 shengjiu.wang@nxp.com
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;
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?