linux-kernel - [PATCH] ASoC: core: restore dpcm flags semantics

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Date:   Wed, 29 Jul 2020 17:46:39 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>
Cc:     Jerome Brunet <jbrunet@...libre.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org, linux-amlogic@...ts.infradead.org,
        Kevin Hilman <khilman@...libre.com>, zhangn1985@...look.com,
        Stephan Gerhold <stephan@...hold.net>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Subject: [PATCH] ASoC: core: restore dpcm flags semantics

commit b73287f0b0745 ('ASoC: soc-pcm: dpcm: fix playback/capture checks')
changed dpcm_playback and dpcm_capture semantic by throwing an error if
these flags are not aligned with DAIs capabilities on the link.

The former semantic did not force the flags and DAI caps to be aligned.
The flag previously allowed card drivers to disable a stream direction on
a link (whether or not such feature is deemed useful).

With change ('ASoC: core: use less strict tests for dailink capabilities')
an error is thrown if the flags and and the DAI caps are not aligned. Those
parameters were not meant to aligned initially. No technical reason was
given about why cards should now be considered "broken" in such condition
is not met, or why it should be considered to be an improvement to enforce
that.

Forcing the flags to be aligned with DAI caps just make the information
the flag carry redundant with DAI caps, breaking a few cards along the way.

This change drops the added error conditions and restore the initial flag
semantics.

Cc: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
---

 Hi Mark,

 Because b73287f0b0745 ('ASoC: soc-pcm: dpcm: fix playback/capture checks')
 introduced more than one problem, the change
 "ASoC: core: use less strict tests for dailink capabilities" [0] is still
 necessary but the change of semantic remains a problem with it.

 This patch applies on top of it.

 sound/soc/soc-pcm.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 00ac1cbf6f88..2e205b738eae 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -2749,13 +2749,6 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 					break;
 				}
 			}
-
-			if (!playback) {
-				dev_err(rtd->card->dev,
-					"No CPU DAIs support playback for stream %s\n",
-					rtd->dai_link->stream_name);
-				return -EINVAL;
-			}
 		}
 		if (rtd->dai_link->dpcm_capture) {
 			stream = SNDRV_PCM_STREAM_CAPTURE;
@@ -2766,13 +2759,6 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 					break;
 				}
 			}
-
-			if (!capture) {
-				dev_err(rtd->card->dev,
-					"No CPU DAIs support capture for stream %s\n",
-					rtd->dai_link->stream_name);
-				return -EINVAL;
-			}
 		}
 	} else {
 		/* Adapt stream for codec2codec links */
-- 
2.25.4