From d2bf75f4f6b277c35eb887859139df7c2d390b87 Mon Sep 17 00:00:00 2001 From: Pierre-Louis Bossart Date: Mon, 14 Jun 2021 13:08:15 -0500 Subject: ASoC: rt711-sdca-sdw: fix race condition on system suspend MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In the initial driver we cancelled deferred work, but there is still a window of time where a new interrupt could result in new deferred work executed after the link is disabled, leading to an IO error. While we did not see this IO error on RT711-sdca-based platforms, the code pattern is similar to the RT700 case where the IO error was noted, so the fix is added for consistency. This patch uses an 'disable_irq_lock' mutex to prevent new interrupts from happening after the start of the system suspend. The choice of a mutex v. a spinlock is mainly due to the time required to clear interrupts, which requires a command to be transmitted by the SoundWire host IP and acknowledged with an interrupt. The 'interrupt_callback' routine is also not meant to be called from an interrupt context. An additional 'disable_irq' flag prevents race conditions where the status changes before the interrupts are disabled, but the workqueue handling status changes is scheduled after the completion of the system suspend. On resume the interrupts are re-enabled already by the io_init routine so we only clear the flag. The code is slightly different from the other codecs since the interrupt callback deals with the SDCA interrupts, leading to a much larger section that's protected by the mutex. The SoundWire interrupt scheme requires a read after clearing a status, it's not clear from the specifications what would happen if SDCA interrupts are disabled in the middle of the sequence, so the entire interrupt status read/write is kept as is, even if in the end we discard the information. BugLink: https://github.com/thesofproject/linux/issues/2943 Fixes: 7ad4d237e7c4 ('ASoC: rt711-sdca: Add RT711 SDCA vendor-specific driver') Signed-off-by: Pierre-Louis Bossart Reviewed-by: Bard Liao Reviewed-by: Péter Ujfalusi Link: https://lore.kernel.org/r/20210614180815.153711-6-pierre-louis.bossart@linux.intel.com Signed-off-by: Mark Brown --- sound/soc/codecs/rt711-sdca.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'sound/soc/codecs/rt711-sdca.c') diff --git a/sound/soc/codecs/rt711-sdca.c b/sound/soc/codecs/rt711-sdca.c index 0b0c230dcf71..2e992589f1e4 100644 --- a/sound/soc/codecs/rt711-sdca.c +++ b/sound/soc/codecs/rt711-sdca.c @@ -1411,6 +1411,8 @@ int rt711_sdca_init(struct device *dev, struct regmap *regmap, rt711->regmap = regmap; rt711->mbq_regmap = mbq_regmap; + mutex_init(&rt711->disable_irq_lock); + /* * Mark hw_init to false * HW init will be performed when device reports present @@ -1494,6 +1496,8 @@ int rt711_sdca_io_init(struct device *dev, struct sdw_slave *slave) int ret = 0; unsigned int val; + rt711->disable_irq = false; + if (rt711->hw_init) return 0; -- cgit