From: Sheetal <sheetal@nvidia.com>

Issue:
 When multiple audio streams share a common BE DAI, the BE DAI
 widget can be powered up before its hardware parameters are configured.
 This incorrect sequence leads to intermittent pcm_write errors.

 For example, the below Tegra use-case throws an error:
  aplay(2 streams) -> AMX(mux) -> ADX(demux) -> arecord(2 streams),
  here, 'AMX TX' and 'ADX RX' are common BE DAIs.

For above usecase when failure happens below sequence is observed:
 aplay(1) FE open()
  - BE DAI callbacks added to the list
  - BE DAI state = SND_SOC_DPCM_STATE_OPEN
 aplay(2) FE open()
  - BE DAI callbacks are not added to the list as the state is
    already SND_SOC_DPCM_STATE_OPEN during aplay(1) FE open().
 aplay(2) FE hw_params()
  - BE DAI hw_params() callback ignored
 aplay(2) FE prepare()
  - Widget is powered ON without BE DAI hw_params() call
 aplay(1) FE hw_params()
  - BE DAI hw_params() is now called

Fix:
 Add BE DAIs in the list if its state is either SND_SOC_DPCM_STATE_OPEN
 or SND_SOC_DPCM_STATE_HW_PARAMS as well.

It ensures the widget is powered ON after BE DAI hw_params() callback.

Fixes: 0c25db3f7621 ("ASoC: soc-pcm: Don't reconnect an already active BE")
Signed-off-by: Sheetal <sheetal@nvidia.com>
---
 sound/soc/soc-pcm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index ebe99d369ca9..d7f6d3a6d312 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1595,10 +1595,13 @@ static int dpcm_add_paths(struct snd_soc_pcm_runtime *fe, int stream,
 		/*
 		 * Filter for systems with 'component_chaining' enabled.
 		 * This helps to avoid unnecessary re-configuration of an
-		 * already active BE on such systems.
+		 * already active BE on such systems and ensures the BE DAI
+		 * widget is powered ON after hw_params() BE DAI callback.
 		 */
 		if (fe->card->component_chaining &&
 		    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_NEW) &&
+		    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_OPEN) &&
+		    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_HW_PARAMS) &&
 		    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_CLOSE))
 			continue;
 
-- 
2.17.1

On Fri, 04 Apr 2025 10:59:53 +0000, Sheetal . wrote:
> Issue:
>  When multiple audio streams share a common BE DAI, the BE DAI
>  widget can be powered up before its hardware parameters are configured.
>  This incorrect sequence leads to intermittent pcm_write errors.
> 
>  For example, the below Tegra use-case throws an error:
>   aplay(2 streams) -> AMX(mux) -> ADX(demux) -> arecord(2 streams),
>   here, 'AMX TX' and 'ADX RX' are common BE DAIs.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: soc-pcm: Fix hw_params() and DAPM widget sequence
      commit: 9aff2e8df240e84a36f2607f98a0a9924a24e65d

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark