[Intel-gfx] [PATCH v2] drm/i915: Limit audio CDCLK>=2*BCLK constraint back to GLK only

[Takashi Iwai]

On Wed, 11 Mar 2020 18:04:24 +0100,
Kai Vehmanen wrote:
> 
> Hey,
> 
> On Wed, 11 Mar 2020, Takashi Iwai wrote:
> 
> > The remaining question is whether this display_power() call is still
> > needed for the recent chips.  Basically it's there for HSW/BDW type
> > chips that need already the power for the HDA link that is dedicated
> > to HDMI.  That is, a patch like below could work for the recent chips
> 
> yes, it is still needed. The newer chips (GLK, ICL and newer) have added 
> sw logic in i915 get_power() that must be run before audio controller is 
> initialized. So calling display_power() here is actually more critical 
> than before, power up from codec driver is too late. If it's not done, 
> you'll get verbs timing out (unless power management is disabled on i915 
> side).

Alright, then it's an unavoidable case.  Then it seems rather natural
to limit the CDCLK statically when the audio device is present on the
system, rather than too frequent up and down...


Takashi