From: Peter Ujfalusi peter.ujfalusi@linux.intel.com
In the existing IPC support, the reply to each IPC message is handled in an IRQ thread. The assumption is that the IRQ thread is scheduled without significant delays.
On an experimental (iow, buggy) kernel, the IRQ thread dealing with the reply to the last IPC message before powering-down the DSP can be delayed by several seconds. The IRQ thread will proceed with register accesses after the DSP is powered-down which results in a kernel crash.
While the bug which causes the delay is not in the audio stack, we must handle such cases with defensive programming to avoid such crashes.
Call synchronize_irq() before proceeding to power down the DSP to make sure that no irq thread is pending execution.
Closes: https://github.com/thesofproject/linux/issues/4608 Reviewed-by: Guennadi Liakhovetski guennadi.liakhovetski@linux.intel.com Signed-off-by: Peter Ujfalusi peter.ujfalusi@linux.intel.com Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- sound/soc/sof/intel/hda-dsp.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/sound/soc/sof/intel/hda-dsp.c b/sound/soc/sof/intel/hda-dsp.c index 44f39a520bb3..2445ae7f6b2e 100644 --- a/sound/soc/sof/intel/hda-dsp.c +++ b/sound/soc/sof/intel/hda-dsp.c @@ -699,6 +699,9 @@ static int hda_suspend(struct snd_sof_dev *sdev, bool runtime_suspend) if (ret < 0) return ret;
+ /* make sure that no irq handler is pending before shutdown */ + synchronize_irq(sdev->ipc_irq); + hda_codec_jack_wake_enable(sdev, runtime_suspend);
/* power down all hda links */