Re: [RFC PATCH v3 3/4] ASoC: fsl_asrc_dma: Reuse the dma channel if available in Back-End

2020-06-12 Thread Nicolin Chen
On Fri, Jun 12, 2020 at 03:37:50PM +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
> 
> 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 

Reviewed-by: Nicolin Chen 


[RFC PATCH v3 3/4] ASoC: fsl_asrc_dma: Reuse the dma channel if available in Back-End

2020-06-12 Thread Shengjiu Wang
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

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 
---
 sound/soc/fsl/fsl_asrc_dma.c | 25 -
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/sound/soc/fsl/fsl_asrc_dma.c b/sound/soc/fsl/fsl_asrc_dma.c
index d6a3fc5f87e5..d88e6343e0a2 100644
--- a/sound/soc/fsl/fsl_asrc_dma.c
+++ b/sound/soc/fsl/fsl_asrc_dma.c
@@ -135,6 +135,8 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component 
*component,
struct snd_dmaengine_dai_dma_data *dma_params_be = NULL;
struct snd_pcm_runtime *runtime = substream->runtime;
struct fsl_asrc_pair *pair = runtime->private_data;
+   struct dma_chan *tmp_chan = NULL, *be_chan = NULL;
+   struct snd_soc_component *component_be = NULL;
struct fsl_asrc *asrc = pair->asrc;
struct dma_slave_config config_fe, config_be;
enum asrc_pair_index index = pair->index;
@@ -142,7 +144,6 @@ 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;
@@ -197,18 +198,30 @@ 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) {
+   be_chan = 
soc_component_to_pcm(component_be)->chan[substream->stream];
+   tmp_chan = be_chan;
+   }
+   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);
+   if (!be_chan)
+   dma_release_channel(tmp_chan);
 
/* Get DMA request of Front-End */
tmp_chan = asrc->get_dma_channel(pair, dir);
@@ -221,6 +234,8 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component 
*component,
pair->dma_chan[dir] =
dma_request_channel(mask, filter, >dma_data);
} else {
+   if (!be_chan)
+   dma_release_channel(tmp_chan);
pair->dma_chan[dir] =
asrc->get_dma_channel(pair, dir);
}
-- 
2.21.0