linux-kernel - [PATCH] ASoC: hdac_hdmi: remove cancel_work

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Message-Id: <1594818110-786-1-git-send-email-brent.lu@intel.com>
Date:   Wed, 15 Jul 2020 21:01:50 +0800
From:   Brent Lu <brent.lu@...el.com>
To:     alsa-devel@...a-project.org
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Amadeusz Sławiński 
        <amadeuszx.slawinski@...ux.intel.com>,
        Guennadi Liakhovetski <guennadi.liakhovetski@...ux.intel.com>,
        Brent Lu <brent.lu@...el.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] ASoC: hdac_hdmi: remove cancel_work_sync in runtime suspend

A deadlock is identified when there are three contexts running at the
same time:
- a HDMI jack work which is calling snd_soc_dapm_sync().
- user space is calling snd_pcm_release() to close pcm device.
- pm is calling runtime suspend function of HDMI codec driver.

By removing the clear_dapm_works() invocation in the
hdac_hdmi_runtime_suspend() function, the snd_pcm_release() could
always returns from dapm_power_widgets() function call without
blocking the hdac_hdmi_jack_dapm_work() work thread or being blocked
by the hdac_hdmi_runtime_suspend() function. The purpose of the jack
work is to enable/disable the dapm jack pin so it's not necessary to
cancel the work in runtime suspend function which is usually called
when pcm device is closed.

Signed-off-by: Brent Lu <brent.lu@...el.com>
---
 sound/soc/codecs/hdac_hdmi.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/sound/soc/codecs/hdac_hdmi.c b/sound/soc/codecs/hdac_hdmi.c
index f26b77f..9052edd 100644
--- a/sound/soc/codecs/hdac_hdmi.c
+++ b/sound/soc/codecs/hdac_hdmi.c
@@ -2097,8 +2097,6 @@ static int hdac_hdmi_runtime_suspend(struct device *dev)
 	if (!bus)
 		return 0;
 
-	clear_dapm_works(hdev);
-
 	/*
 	 * Power down afg.
 	 * codec_read is preferred over codec_write to set the power state.
-- 
2.7.4