[RFC PATCH] ASoC: fsl_asrc_dma: Fix warning "Cannot create DMA dma:tx symlink"

[RFC PATCH] ASoC: fsl_asrc_dma: Fix warning "Cannot create DMA dma:tx symlink"

[Shengjiu Wang]

The issue log is:

[   48.021506] CPU: 0 PID: 664 Comm: aplay Not tainted 5.7.0-rc1-13120-g12b434cbbea0 #343
[   48.031063] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[   48.037638] [<c0110dd8>] (unwind_backtrace) from [<c010b8ec>] (show_stack+0x10/0x14)
[   48.045413] [<c010b8ec>] (show_stack) from [<c0557fc0>] (dump_stack+0xe4/0x118)
[   48.052757] [<c0557fc0>] (dump_stack) from [<c032aeb4>] (sysfs_warn_dup+0x50/0x64)
[   48.060357] [<c032aeb4>] (sysfs_warn_dup) from [<c032b1a8>] (sysfs_do_create_link_sd+0xc8/0xd4)
[   48.069086] [<c032b1a8>] (sysfs_do_create_link_sd) from [<c05dc668>] (dma_request_chan+0xb0/0x210)
[   48.078068] [<c05dc668>] (dma_request_chan) from [<c05dc7d0>] (dma_request_slave_channel+0x8/0x14)
[   48.087060] [<c05dc7d0>] (dma_request_slave_channel) from [<c09d5cd4>] (fsl_asrc_dma_hw_params+0x1dc/0x434)
[   48.096831] [<c09d5cd4>] (fsl_asrc_dma_hw_params) from [<c09c143c>] (soc_pcm_hw_params+0x4b0/0x650)
[   48.105903] [<c09c143c>] (soc_pcm_hw_params) from [<c09c36a8>] (dpcm_fe_dai_hw_params+0x70/0xe4)
[   48.114715] [<c09c36a8>] (dpcm_fe_dai_hw_params) from [<c099b274>] (snd_pcm_hw_params+0x158/0x418)
[   48.123701] [<c099b274>] (snd_pcm_hw_params) from [<c099c5a0>] (snd_pcm_ioctl+0x734/0x183c)
[   48.132079] [<c099c5a0>] (snd_pcm_ioctl) from [<c029ff94>] (ksys_ioctl+0x2ac/0xb98)
[   48.139765] [<c029ff94>] (ksys_ioctl) from [<c0100080>] (ret_fast_syscall+0x0/0x28)
[   48.147440] Exception stack(0xed3c5fa8 to 0xed3c5ff0)
[   48.152515] 5fa0:                   bec28670 00e92870 00000004 c25c4111 bec28670 0002000f
[   48.160716] 5fc0: bec28670 00e92870 00e92820 00000036 0000bb80 00000000 0002c2f8 00000003
[   48.168913] 5fe0: b6f4d3fc bec2853c b6ee7655 b6e22cf8
[   48.174236] fsl-esai-dai 2024000.esai: Cannot create DMA dma:tx symlink

The dma channel is already requested by Back-End cpu dai driver,
if fsl_asrc_dma requests dma chan with same dma:tx symlink, then
this warning comes out.

The warning is added by
commit 71723a96b8b1 ("dmaengine: Create symlinks between DMA channels and slaves")
commit bad83565eafe ("dmaengine: Cleanups for the slave <-> channel symlink support")

As the dma channel is requested by Back-End, we need to reuse the channel
and avoid to request a new one, then the issue can be fixed.

In order to get the dma channel which is already requested in Back-End.
we export 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>
---
 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          | 49 +++++++++++++++++++++------
 sound/soc/soc-core.c                  |  3 +-
 sound/soc/soc-generic-dmaengine-pcm.c | 12 -------
 6 files changed, 55 insertions(+), 24 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/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/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..3ad862225326 100644
--- a/sound/soc/fsl/fsl_asrc_dma.c
+++ b/sound/soc/fsl/fsl_asrc_dma.c
@@ -135,6 +135,7 @@ 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 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 +143,7 @@ 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 dma_chan *tmp_chan = NULL, *tmp_chan_new = NULL;
 	struct device *dev_be;
 	u8 dir = tx ? OUT : IN;
 	dma_cap_mask_t mask;
@@ -160,6 +161,7 @@ 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);
 		break;
 	}
 
@@ -205,10 +207,16 @@ 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 (component_be)
+			tmp_chan = soc_component_to_pcm(component_be)->chan[substream->stream];
+		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 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;
+		if (component_be)
+			pair->dma_chan[dir] = soc_component_to_pcm(component_be)->chan[substream->stream];;
+		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]) {
@@ -273,19 +298,21 @@ 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;
 }
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)
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

Re: [RFC PATCH] ASoC: fsl_asrc_dma: Fix warning "Cannot create DMA dma:tx symlink"

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 1413 bytes --]

On Mon, Jun 08, 2020 at 03:07:00PM +0800, Shengjiu Wang wrote:
> The issue log is:
> 
> [   48.021506] CPU: 0 PID: 664 Comm: aplay Not tainted 5.7.0-rc1-13120-g12b434cbbea0 #343
> [   48.031063] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
> [   48.037638] [<c0110dd8>] (unwind_backtrace) from [<c010b8ec>] (show_stack+0x10/0x14)
> [   48.045413] [<c010b8ec>] (show_stack) from [<c0557fc0>] (dump_stack+0xe4/0x118)

Please think hard before including complete backtraces in upstream
reports, they are very large and contain almost no useful information
relative to their size so often obscure the relevant content in your
message. If part of the backtrace is usefully illustrative (it often is
for search engines if nothing else) then it's usually better to pull out
the relevant sections.

> ---
>  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          | 49 +++++++++++++++++++++------
>  sound/soc/soc-core.c                  |  3 +-
>  sound/soc/soc-generic-dmaengine-pcm.c | 12 -------
>  6 files changed, 55 insertions(+), 24 deletions(-)

Please split the core changes you are adding from the driver changes
that use them.

The change does look reasonable for the issue, it's not ideal but I'm
not sure it's avoidable with DPCM.

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