[Intel-gfx] [PATCH] drm/i915: preserve pipe A quirk in i9xx_set_pipeconf

[Chris Wilson]

On Tue, Sep 24, 2013 at 11:46:14AM +0200, Daniel Vetter wrote:
> This regression has been introduced in
> 
> commit 9f11a9e4e50006b615ba94722dfc33ced89664cf
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Thu Jun 13 00:54:58 2013 +0200
> 
>     drm/i915: set up PIPECONF explicitly for i9xx/vlv platforms
> 
> Ville brough up the idea that this is just the pipe A quirk gone
> wrong.
> 
> Note that after resume the bios might or might not have enabled pipe A
> already.  We have a bit of magic to make sure that on resume we set up
> a decent mode for pipe A, but I fear if I just smash pipe A to always
> on we'd enable it in a bogus state and hang the hw. Hence the
> readback.
> 
> v2: Clarify the logic a bit as suggested by Chris. Also amend the
> commit message to clarify why we don't unconditionally enable the
> pipe.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=66462
> References: https://lkml.org/lkml/2013/8/26/238
> Cc: Meelis Roos <mroos at ut.ee>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

would still prefer pipeconf |= PIPECONF_ENABLE though.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre