[1/2] ASoC: AMD: Fix simultaneous playback and capture on different channel
diff mbox series

Message ID 1536566815-3271-1-git-send-email-akshu.agrawal@amd.com
State New
Headers show
Series
  • [1/2] ASoC: AMD: Fix simultaneous playback and capture on different channel
Related show

Commit Message

Agrawal, Akshu Sept. 10, 2018, 8:06 a.m. UTC
If capture and playback are started on different channel (I2S/BT)
there is a possibilty that channel information passed from machine driver
is overwritten before the configuration is done in dma driver.
Example:
113.597588: cz_max_startup: ---playback sets BT channel
113.597694: cz_dmic1_startup: ---capture sets I2S channel
113.597979: acp_dma_hw_params: ---configures capture for I2S channel
113.598114: acp_dma_hw_params: ---configures playback for I2S channel

This is fixed by having lock between startup and prepare. This ensures
no other codec startup gets called between a codec's startup(where channel
info is set) and hw_params(where channel info is read).

Signed-off-by: Akshu Agrawal <akshu.agrawal@amd.com>
---
 sound/soc/amd/acp-da7219-max98357a.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

Comments

Mark Brown Sept. 10, 2018, 11:38 a.m. UTC | #1
On Mon, Sep 10, 2018 at 01:36:29PM +0530, Akshu Agrawal wrote:
> If capture and playback are started on different channel (I2S/BT)
> there is a possibilty that channel information passed from machine driver
> is overwritten before the configuration is done in dma driver.
> Example:
> 113.597588: cz_max_startup: ---playback sets BT channel
> 113.597694: cz_dmic1_startup: ---capture sets I2S channel
> 113.597979: acp_dma_hw_params: ---configures capture for I2S channel
> 113.598114: acp_dma_hw_params: ---configures playback for I2S channel
> 
> This is fixed by having lock between startup and prepare. This ensures
> no other codec startup gets called between a codec's startup(where channel
> info is set) and hw_params(where channel info is read).

This isn't viable - the driver will deadlock if the application hits an
error and never gets to startup, or if the application tries to
simultaneously configure two channels (ie, do all the prepares and then
all the parameter configuration and then startup).  The DMA driver needs
to remember the configurations for the different channels separately.
Agrawal, Akshu Sept. 10, 2018, 5:21 p.m. UTC | #2
On 9/10/2018 5:08 PM, Mark Brown wrote:
> On Mon, Sep 10, 2018 at 01:36:29PM +0530, Akshu Agrawal wrote:
>> If capture and playback are started on different channel (I2S/BT)
>> there is a possibilty that channel information passed from machine driver
>> is overwritten before the configuration is done in dma driver.
>> Example:
>> 113.597588: cz_max_startup: ---playback sets BT channel
>> 113.597694: cz_dmic1_startup: ---capture sets I2S channel
>> 113.597979: acp_dma_hw_params: ---configures capture for I2S channel
>> 113.598114: acp_dma_hw_params: ---configures playback for I2S channel
>>
>> This is fixed by having lock between startup and prepare. This ensures
>> no other codec startup gets called between a codec's startup(where channel
>> info is set) and hw_params(where channel info is read).
> 
> This isn't viable - the driver will deadlock if the application hits an
> error and never gets to startup, or if the application tries to
> simultaneously configure two channels (ie, do all the prepares and then
> all the parameter configuration and then startup).

We can avoid deadlock by having another mutex_unlock in the shutdown
call of each of codec's ops. Wouldn't in all possible termination
scenarios, it will cleanup and exit via shutdown callback?

Having said that I think there is a better approach to this, is by
having 2 separate instance variable for playback and capture for passing
instance info from machine driver to dma driver. Respective codec in
machine driver will set the capture/playback instance. dma driver on the
basis of substream->stream can read the correct one. No fear of deadlock
in this.

Thanks,
Akshu

Patch
diff mbox series

diff --git a/sound/soc/amd/acp-da7219-max98357a.c b/sound/soc/amd/acp-da7219-max98357a.c
index 3879ccc..b98ffbc 100644
--- a/sound/soc/amd/acp-da7219-max98357a.c
+++ b/sound/soc/amd/acp-da7219-max98357a.c
@@ -47,6 +47,7 @@ 
 
 static struct snd_soc_jack cz_jack;
 static struct clk *da7219_dai_clk;
+static struct mutex instance_lock;
 extern int bt_uart_enable;
 
 static int cz_da7219_init(struct snd_soc_pcm_runtime *rtd)
@@ -150,6 +151,7 @@  static int cz_da7219_startup(struct snd_pcm_substream *substream)
 	snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
 				   &constraints_rates);
 
+	mutex_lock(&instance_lock);
 	machine->i2s_instance = I2S_SP_INSTANCE;
 	machine->capture_channel = CAP_CHANNEL1;
 	return da7219_clk_enable(substream);
@@ -160,6 +162,12 @@  static void cz_da7219_shutdown(struct snd_pcm_substream *substream)
 	da7219_clk_disable();
 }
 
+static int cz_da7219_prepare(struct snd_pcm_substream *substream)
+{
+	mutex_unlock(&instance_lock);
+	return 0;
+}
+
 static int cz_max_startup(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
@@ -177,6 +185,7 @@  static int cz_max_startup(struct snd_pcm_substream *substream)
 	snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
 				   &constraints_rates);
 
+	mutex_lock(&instance_lock);
 	machine->i2s_instance = I2S_BT_INSTANCE;
 	return da7219_clk_enable(substream);
 }
@@ -186,6 +195,12 @@  static void cz_max_shutdown(struct snd_pcm_substream *substream)
 	da7219_clk_disable();
 }
 
+static int cz_max_prepare(struct snd_pcm_substream *substream)
+{
+	mutex_unlock(&instance_lock);
+	return 0;
+}
+
 static int cz_dmic0_startup(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
@@ -203,6 +218,7 @@  static int cz_dmic0_startup(struct snd_pcm_substream *substream)
 	snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
 				   &constraints_rates);
 
+	mutex_lock(&instance_lock);
 	machine->i2s_instance = I2S_BT_INSTANCE;
 	return da7219_clk_enable(substream);
 }
@@ -224,6 +240,7 @@  static int cz_dmic1_startup(struct snd_pcm_substream *substream)
 	snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
 				   &constraints_rates);
 
+	mutex_lock(&instance_lock);
 	machine->i2s_instance = I2S_SP_INSTANCE;
 	machine->capture_channel = CAP_CHANNEL0;
 	return da7219_clk_enable(substream);
@@ -234,24 +251,34 @@  static void cz_dmic_shutdown(struct snd_pcm_substream *substream)
 	da7219_clk_disable();
 }
 
+static int cz_dmic_prepare(struct snd_pcm_substream *substream)
+{
+	mutex_unlock(&instance_lock);
+	return 0;
+}
+
 static const struct snd_soc_ops cz_da7219_cap_ops = {
 	.startup = cz_da7219_startup,
 	.shutdown = cz_da7219_shutdown,
+	.prepare = cz_da7219_prepare,
 };
 
 static const struct snd_soc_ops cz_max_play_ops = {
 	.startup = cz_max_startup,
 	.shutdown = cz_max_shutdown,
+	.prepare = cz_max_prepare,
 };
 
 static const struct snd_soc_ops cz_dmic0_cap_ops = {
 	.startup = cz_dmic0_startup,
 	.shutdown = cz_dmic_shutdown,
+	.prepare = cz_dmic_prepare,
 };
 
 static const struct snd_soc_ops cz_dmic1_cap_ops = {
 	.startup = cz_dmic1_startup,
 	.shutdown = cz_dmic_shutdown,
+	.prepare = cz_dmic_prepare,
 };
 
 static struct snd_soc_dai_link cz_dai_7219_98357[] = {
@@ -409,6 +436,7 @@  static int cz_probe(struct platform_device *pdev)
 	card = &cz_card;
 	cz_card.dev = &pdev->dev;
 	platform_set_drvdata(pdev, card);
+	mutex_init(&instance_lock);
 	snd_soc_card_set_drvdata(card, machine);
 	ret = devm_snd_soc_register_card(&pdev->dev, &cz_card);
 	if (ret) {