linux-kernel - [PATCH 3/6] ASoC: cs35l56: Skip first init_completion wait in dsp_work if init

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Date:   Tue, 11 Apr 2023 16:25:25 +0100
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <broonie@...nel.org>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH 3/6] ASoC: cs35l56: Skip first init_completion wait in dsp_work if init_done

At the start of dsp_work() only wait for init_completion if !init_done.
This allows system suspend to re-queue dsp_work() without having to
do a dummy complete() of init_completion.

A dummy completion in system suspend would have to be conditional on
init_done. But that would create a possible race condition between our
system resume and cs35l56_init() in the corner case that we suspend right
after the SoundWire core has enumerated and reported ATTACHED.

It is safer and simpler to have cs35l56_init() as the only place that
init_completion is completed, and dsp_work() as the only place that
it is consumed.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
---
 sound/soc/codecs/cs35l56.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/cs35l56.c b/sound/soc/codecs/cs35l56.c
index 997a5c5acaab..62c44276c121 100644
--- a/sound/soc/codecs/cs35l56.c
+++ b/sound/soc/codecs/cs35l56.c
@@ -866,7 +866,8 @@ static void cs35l56_dsp_work(struct work_struct *work)
 	unsigned int val;
 	int ret = 0;

-	if (!wait_for_completion_timeout(&cs35l56->init_completion,
+	if (!cs35l56->init_done &&
+	    !wait_for_completion_timeout(&cs35l56->init_completion,
 					 msecs_to_jiffies(5000))) {
 		dev_err(cs35l56->dev, "%s: init_completion timed out\n", __func__);
 		goto complete;
-- 
2.30.2