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Date: Fri, 12 Jun 2020 15:37:50 +0800 From: Shengjiu Wang <shengjiu.wang@....com> To: lars@...afoo.de, perex@...ex.cz, tiwai@...e.com, lgirdwood@...il.com, broonie@...nel.org, timur@...nel.org, nicoleotsuka@...il.com, Xiubo.Lee@...il.com, festevam@...il.com, alsa-devel@...a-project.org, linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org Subject: [RFC PATCH v3 3/4] ASoC: fsl_asrc_dma: Reuse the dma channel if available in Back-End 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 <shengjiu.wang@....com> --- 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, &pair->dma_data); } else { + if (!be_chan) + dma_release_channel(tmp_chan); pair->dma_chan[dir] = asrc->get_dma_channel(pair, dir); } -- 2.21.0
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