[Intel-gfx] [PATCH 08/17] drm/i915: Move the tracking of dpms_mode down into crtc enable/disable

[Chris Wilson]

On Wed, 04 May 2011 12:10:06 -0700, Keith Packard <keithp at keithp.com> wrote:
> On Thu, 21 Apr 2011 22:18:23 +0100, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> 
> > As we failed to update the dpms_mode after modeset, where it is presumed
> > to have been changed to DRM_MODE_DPMS_ON by the upper layers the dpms state
> > on the crtc became inconsistent with its actual active state. This
> > notably confused code and left the pipe active when it was meant to be
> > disabled, leading to PGTBL_ER if the fb was subsequently moved.
> > 
> > As we use the dpms_mode state for restoring the crtc after load-detection,
> > we can not simply remove it in favour of simply using the active
> > state.
> 
> I don't understand this comment -- this patch changes the code so that
> dpms_mode exactly tracks active, instead of tracking the desired DPMS state.

Indeed for our purposes of tracking the register states, we do not want to
track the desired mode and only the actual state of the crtc. Yes, it is
active by another value. I was tempted to do a more complicated patch to
remove one of the two tracking variables.

We can remove dpms_mode in favour of solely using active.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre