[Intel-gfx] [PATCH v2 1/2] drm/i915: provide interface for audio driver to query cdclk

[Lin, Mengdong]

Hi Jani,

> -----Original Message-----
> From: Nikula, Jani
> Sent: Thursday, July 03, 2014 3:33 PM
 
> I wrote this as a quick hack patch to try as an alternative to [1] which
> ended up not working on Haswell. Please reassure me that this is going to
> be a temporary solution until we get a more generic interface between the
> audio and display drivers. I don't much like this, but at least it's isolated
> and small.

Sure. We'll clean up code when the generic interface is ready. 
This is only a temporary solution, safer than the BIOS notifications.

And would you like to further revise this patch? 
But please keep this API not changed at the moment since the audio driver already queries the symbol name.

Thanks
Mengdong

> I'd like the commit message amended with something like:
> 
> """
> If the display power well has been disabled, the display audio controller
> divider values EM4 MVALUE and EM5 NVALUE will have been lost. The
> CDCLK frequency is required for reprogramming them. Provide a private
> interface for the audio driver to query CDCLK.
> 
> This is a stopgap solution until a more generic interface between audio
> and display drivers has been implemented.
> """
> 
> I'd also like to have an additional Reviewed-by from the i915 side. After
> that, I'm fine with merging this through alsa.