[Intel-gfx] [PATCH 15/19] drm/i915: HSW cdclk support

[Daniel Vetter]

On Thu, Apr 09, 2015 at 10:24:24AM +0300, Mika Kahola wrote:
> I did some testing on audio part with HDMI-HDMI and DP-HDMI cables
> connected to my Haswell box. Before applying the patch I tested as a
> reference with the latest -nightly (04-08-2015), 4.0-rc7. Unfortunately,
> I failed to get any audio over HDMI cable. For a reference I tested with
> the very same setup the vanillla kernel from Linus tree 4.0-rc7 and with
> that kernel the audio worked ok. Then I did some GIT bisecting and it
> turned out that the first commit that I failed to get audio working was
> aa2fee4286e43b4784982b17669b02cc99c1ae55.

I don't have this sha1 anywhere. Can you please double-check?

Also to avoid such issues please always add at least the commit subject
and author, so that I can find it if it's somehow rebased.
-Daniel

> 
> To test this patch audio functionality I checkout the -nightly version
> that works for me and apply the patch and test it. I'll come back with
> the results later on. 
> 
> I had the module option i915.disable_power_well=0
> 
> The test routine that I used for audio testing was
> speaker-test -c 2 -r 48000 -f S16_LE -t pink --device=plughw:0,3
> 
> On Tue, 2015-04-07 at 15:52 +0200, Daniel Vetter wrote:
> > On Tue, Apr 07, 2015 at 12:29:25PM +0300, Mika Kahola wrote:
> > > Definitely a good idea to check the audio part as well if there is
> > > a doubt that by changing CD clock the audio would fail. I can check
> > > this and I'll get back once I have the results.
> > 
> > We force a full modeset, which should result in an interrupt on the audio
> > side, which should result in the audio driver re-reading the current
> > cdclk. If that's no the case it's buggy already.
> > -Daniel
> 
> -- 
> Mika Kahola, Intel OTC
> 
> 
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch