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Unverified Commit e2803e61 authored by Keyon Jie's avatar Keyon Jie Committed by Mark Brown
Browse files

ASoC: SOF: PCM: add period_elapsed work to fix race condition in interrupt context 



The IPC implementation in SOF requires sending IPCs serially: we should
not send a new IPC command to the firmware before we get an ACK (or time
out) from firmware, and the IRQ processing is complete.

snd_pcm_period_elapsed() can be called in interrupt context before
IRQ_HANDLED is returned. When the PCM is done draining, a STOP
IPC will then be sent, which breaks the expectation that IPCs are
handled serially and leads to IPC timeouts.

This patch adds a workqueue to defer the call to snd_pcm_elapsed() after
the IRQ is handled.

Signed-off-by: default avatarKeyon Jie <yang.jie@linux.intel.com>
Signed-off-by: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent b0056fda

sound/soc/sof/pcm.c

+48 −0
Original line number Diff line number Diff line
@@ -52,6 +52,48 @@ static int sof_pcm_dsp_params(struct snd_sof_pcm *spcm, struct snd_pcm_substream 
	return ret;

}



/*

 * sof pcm period elapse work

 */

static void sof_pcm_period_elapsed_work(struct work_struct *work)

{

	struct snd_sof_pcm_stream *sps =

		container_of(work, struct snd_sof_pcm_stream,

			     period_elapsed_work);



	snd_pcm_period_elapsed(sps->substream);

}



/*

 * sof pcm period elapse, this could be called at irq thread context.

 */

void snd_sof_pcm_period_elapsed(struct snd_pcm_substream *substream)

{

	struct snd_soc_pcm_runtime *rtd = substream->private_data;

	struct snd_soc_component *component =

		snd_soc_rtdcom_lookup(rtd, DRV_NAME);

	struct snd_sof_dev *sdev = snd_soc_component_get_drvdata(component);

	struct snd_sof_pcm *spcm;



	spcm = snd_sof_find_spcm_dai(sdev, rtd);

	if (!spcm) {

		dev_err(sdev->dev,

			"error: period elapsed for unknown stream!\n");

		return;

	}



	/*

	 * snd_pcm_period_elapsed() can be called in interrupt context

	 * before IRQ_HANDLED is returned. Inside snd_pcm_period_elapsed(),

	 * when the PCM is done draining or xrun happened, a STOP IPC will

	 * then be sent and this IPC will hit IPC timeout.

	 * To avoid sending IPC before the previous IPC is handled, we

	 * schedule delayed work here to call the snd_pcm_period_elapsed().

	 */

	schedule_work(&spcm->stream[substream->stream].period_elapsed_work);

}

EXPORT_SYMBOL(snd_sof_pcm_period_elapsed);



/* this may get called several times by oss emulation */

static int sof_pcm_hw_params(struct snd_pcm_substream *substream,

			     struct snd_pcm_hw_params *params)
@@ -169,6 +211,9 @@ static int sof_pcm_hw_params(struct snd_pcm_substream *substream, 
	/* save pcm hw_params */

	memcpy(&spcm->params[substream->stream], params, sizeof(*params));



	INIT_WORK(&spcm->stream[substream->stream].period_elapsed_work,

		  sof_pcm_period_elapsed_work);



	return ret;

}
@@ -203,6 +248,9 @@ static int sof_pcm_hw_free(struct snd_pcm_substream *substream) 
				 sizeof(stream), &reply, sizeof(reply));



	snd_pcm_lib_free_pages(substream);



	cancel_work_sync(&spcm->stream[substream->stream].period_elapsed_work);



	return ret;

}

sound/soc/sof/sof-priv.h

+2 −0
Original line number Diff line number Diff line
@@ -274,6 +274,7 @@ struct snd_sof_pcm_stream { 
	struct snd_dma_buffer page_table;

	struct sof_ipc_stream_posn posn;

	struct snd_pcm_substream *substream;

	struct work_struct period_elapsed_work;

};



/* ALSA SOF PCM device */
@@ -495,6 +496,7 @@ struct snd_sof_pcm *snd_sof_find_spcm_comp(struct snd_sof_dev *sdev, 
					   int *direction);

struct snd_sof_pcm *snd_sof_find_spcm_pcm_id(struct snd_sof_dev *sdev,

					     unsigned int pcm_id);

void snd_sof_pcm_period_elapsed(struct snd_pcm_substream *substream);



/*

 * Stream IPC