Commit 0a0d1740 authored by Pierre-Louis Bossart's avatar Pierre-Louis Bossart Committed by Vinod Koul
Browse files

soundwire: intel: don't save hw_params for use in prepare 



The existing code copies the hw_params pointer and reuses it later in
.prepare, specifically to re-initialize the ALH DMA channel
information that's lost in suspend-resume cycles.

This is not needed, we can directly access the information from the
substream/rtd - as done for the HDAudio DAIs in
sound/soc/sof/intel/hda-dai.c

In addition, using the saved pointer causes the suspend-resume test
cases to fail on specific platforms, depending on which version of GCC
is used. Péter Ujfalusi and I have spent long hours to root-cause this
problem that was reported by the Intel CI first with 6.2-rc1 and again
v6.3-rc1. In the latter case we were lucky that the problem was 100%
reproducible on local test devices, and found out that adding a
dev_dbg() or adding a call to usleep_range() just before accessing the
saved pointer "fixed" the issue. With errors appearing just by
changing the compiler version or minor changes in the code generated,
clearly we have a memory management Heisenbug.

The root-cause seems to be that the hw_params pointer is not
persistent. The soc-pcm code allocates the hw_params structure on the
stack, and passes it to the BE dailink hw_params and DAIs
hw_params. Saving such a pointer and reusing it later during the
.prepare stage cannot possibly work reliably, it's broken-by-design
since v5.10. It's astonishing that the problem was not seen earlier.

This simple fix will have to be back-ported to -stable, due to changes
to avoid the use of the get/set_dmadata routines this patch will only
apply on kernels older than v6.1.

Fixes: a5a0239c ("soundwire: intel: reinitialize IP+DSP in .prepare(), but only when resuming")
Signed-off-by: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: default avatarRanjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: default avatarPéter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: default avatarBard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20230321022642.1426611-1-yung-chuan.liao@linux.intel.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent d005ea71

drivers/soundwire/cadence_master.h

+0 −2
Original line number Diff line number Diff line
@@ -84,7 +84,6 @@ struct sdw_cdns_stream_config { 
 * @bus: Bus handle

 * @stream_type: Stream type

 * @link_id: Master link id

 * @hw_params: hw_params to be applied in .prepare step

 * @suspended: status set when suspended, to be used in .prepare

 * @paused: status set in .trigger, to be used in suspend

 * @direction: stream direction
@@ -96,7 +95,6 @@ struct sdw_cdns_dai_runtime { 
	struct sdw_bus *bus;

	enum sdw_stream_type stream_type;

	int link_id;

	struct snd_pcm_hw_params *hw_params;

	bool suspended;

	bool paused;

	int direction;

drivers/soundwire/intel.c

+7 −4
Original line number Diff line number Diff line
@@ -725,7 +725,6 @@ static int intel_hw_params(struct snd_pcm_substream *substream, 
	dai_runtime->paused = false;

	dai_runtime->suspended = false;

	dai_runtime->pdi = pdi;

	dai_runtime->hw_params = params;



	/* Inform DSP about PDI stream number */

	ret = intel_params_stream(sdw, substream->stream, dai, params,
@@ -778,6 +777,11 @@ static int intel_prepare(struct snd_pcm_substream *substream, 
	}



	if (dai_runtime->suspended) {

		struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);

		struct snd_pcm_hw_params *hw_params;



		hw_params = &rtd->dpcm[substream->stream].hw_params;



		dai_runtime->suspended = false;



		/*
@@ -789,7 +793,7 @@ static int intel_prepare(struct snd_pcm_substream *substream, 
		 */



		/* configure stream */

		ch = params_channels(dai_runtime->hw_params);

		ch = params_channels(hw_params);

		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)

			dir = SDW_DATA_DIR_RX;

		else
@@ -801,7 +805,7 @@ static int intel_prepare(struct snd_pcm_substream *substream, 


		/* Inform DSP about PDI stream number */

		ret = intel_params_stream(sdw, substream->stream, dai,

					  dai_runtime->hw_params,

					  hw_params,

					  sdw->instance,

					  dai_runtime->pdi->intel_alh_id);

	}
@@ -840,7 +844,6 @@ intel_hw_free(struct snd_pcm_substream *substream, struct snd_soc_dai *dai) 
		return ret;

	}



	dai_runtime->hw_params = NULL;

	dai_runtime->pdi = NULL;



	return 0;