[PATCH] ASoC: soc-pcm: Fix hw_params() and DAPM widget sequence

[Sheetal .]

From: Sheetal <sheetal@xxxxxxxxxx>

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@xxxxxxxxxx>
---
 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