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[216.228.112.21]) by smtp.gmail.com with ESMTPSA id y6sm4433379pfp.144.2020.06.11.17.31.14 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 11 Jun 2020 17:31:15 -0700 (PDT) Date: Thu, 11 Jun 2020 17:31:04 -0700 From: Nicolin Chen To: Shengjiu Wang Subject: Re: [RFC PATCH v2 3/3] ASoC: fsl_asrc_dma: Reuse the dma channel if available in Back-End Message-ID: <20200612003103.GA28228@Asurada-Nvidia> References: <0473d4191ae04ab711d63c5c875e47f45f598137.1591783089.git.shengjiu.wang@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0473d4191ae04ab711d63c5c875e47f45f598137.1591783089.git.shengjiu.wang@nxp.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org, lars@metafoo.de, timur@kernel.org, Xiubo.Lee@gmail.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, lgirdwood@gmail.com, tiwai@suse.com, broonie@kernel.org, perex@perex.cz, festevam@gmail.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 > --- > 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?