[alsa-devel] HD-Audio: Is it okay to delay resuming codecs when resuming from S3?

[Takashi Iwai]

At Tue, 26 Nov 2013 07:16:59 +0000,
Lin, Mengdong wrote:
> 
> Hi Takashi,
> 
> Is it okay to delay resuming codecs when resuming from S3? i.e. skip snd_hda_resume() in azx_resume()?
> 
> This would reduce driver resume time from S3. And the codecs will be resumed when being used for the 1st time after S3.
> 
> Resuming a codec may cost more than 100ms. So even if we parallel resuming codecs in snd_hda_resume(), driver resume time on some platforms is still a bit long.

This causes problems on some hardware, e.g. inconsistent mute LEDs.
So you cannot do it unconditionally.  We did it in the past, but had
to switch the forced resume later.

Maybe we can add a flag indicating that the codec resume may be
delayed.  Then the bus resume checks the flags and skips the codec
resume if it's set.


Takashi