[PATCH] ALSA: hda: Avoid unsol event during RPM suspending

[Takashi Iwai]

On Mon, 28 Mar 2022 11:14:11 +0200,
Mohan Kumar wrote:
> 
> There is a corner case with unsol event handling during codec runtime
> suspending state. When the codec runtime suspend call initiated, the
> codec->in_pm atomic variable would be 0, currently the codec runtime
> suspend function calls snd_hdac_enter_pm() which will just increments
> the codec->in_pm atomic variable. Consider unsol event happened just
> after this step and before snd_hdac_leave_pm() in the codec runtime
> suspend function. The snd_hdac_power_up_pm() in the unsol event
> flow in hdmi_present_sense_via_verbs() function would just increment
> the codec->in_pm atomic variable without calling pm_runtime_get_sync
> function.
> 
> As codec runtime suspend flow is already in progress and in parallel
> unsol event is also accessing the codec verbs, as soon as codec
> suspend flow completes and clocks are  switched off before completing
> the unsol event handling as both functions doesn't wait for each other.
> This will result in below errors
> 
> [  589.428020] tegra-hda 3510000.hda: azx_get_response timeout, switching
> to polling mode: last cmd=0x505f2f57
> [  589.428344] tegra-hda 3510000.hda: spurious response 0x80000074:0x5,
> last cmd=0x505f2f57
> [  589.428547] tegra-hda 3510000.hda: spurious response 0x80000065:0x5,
> last cmd=0x505f2f57
> 
> To avoid this, the unsol event flow should not perform any codec verb
> related operations during RPM_SUSPENDING state.
> 
> Signed-off-by: Mohan Kumar <mkumard at nvidia.com>

Thanks, that's a hairy problem...

The logic sounds good, but can we check the PM state before calling
snd_hda_power_up_pm()?


Takashi