From: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com

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: a5a0239c27fe ("soundwire: intel: reinitialize IP+DSP in .prepare(), but only when resuming") Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com Reviewed-by: Ranjani Sridharan ranjani.sridharan@linux.intel.com Reviewed-by: Péter Ujfalusi peter.ujfalusi@linux.intel.com Signed-off-by: Bard Liao yung-chuan.liao@linux.intel.com --- drivers/soundwire/cadence_master.h | 2 -- drivers/soundwire/intel.c | 11 +++++++---- 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/soundwire/cadence_master.h b/drivers/soundwire/cadence_master.h index b653734085d9..27c56274217f 100644 --- a/drivers/soundwire/cadence_master.h +++ b/drivers/soundwire/cadence_master.h @@ -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; diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c index 046c67a2a39b..238acf5c97a9 100644 --- a/drivers/soundwire/intel.c +++ b/drivers/soundwire/intel.c @@ -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;