[alsa-devel] [PATCH] ALSA: hda - Force polling mode on CFL for fixing codec communication

[Takashi Iwai]

On Wed, 21 Mar 2018 10:39:35 +0100,
Ughreja, Rakesh A wrote:
> 
> 
> 
> >-----Original Message-----
> >From: alsa-devel-bounces at alsa-project.org [mailto:alsa-devel-bounces at alsa-
> >project.org] On Behalf Of Takashi Iwai
> >Sent: Wednesday, March 21, 2018 2:45 PM
> >To: alsa-devel at alsa-project.org
> >Cc: Hui Wang <hui.wang at canonical.com>
> >Subject: [alsa-devel] [PATCH] ALSA: hda - Force polling mode on CFL for fixing
> >codec communication
> >
> >We've observed too long probe time with Coffee Lake machines, and the
> >likely cause is some communication problem between the HD-audio
> >controller and the codec chips.  While the controller expects an IRQ
> >wakeup for each codec response, it seems sometimes missing, and it
> >takes one second for the controller driver to time out and read the
> >response in the polling mode.
> >
> 
> I think I faced similar problem while doing the HDA ASoC work.
> 
> I don't have any way to reproduce and test this. Can we increase
> the delay after the link is powered ON. The present delay is 100usec,
> can we make it 521 uSec ? Possibly the codec is not ready after
> the link is powered on and so it's not responding.

I'm afraid that this wouldn't help since the issue appears repeatedly
at later points.

But still it's worth to try.  Hui, could you investigate?


thanks,

Takashi

> 
> File: hda_intel.c
> 
> 	/* 4. turn link up: set SPA to 1 and wait CPA to 1 */
> 	intel_ml_lctl_set_power(chip, 1);
> 	udelay(100); --> change this to 521.
> 
> Regards,
> Rakesh
>