[Intel-gfx] [PATCH 1/2] drm/i915: Force explicit bpp selection for intel_dp_link_required

[Daniel Vetter]

On Mon, Feb 06, 2012 at 12:12:16PM +0000, Dave Airlie wrote:
> On Fri, Jan 27, 2012 at 10:30 AM, Daniel Vetter <daniel at ffwll.ch> wrote:
> > On Wed, Jan 25, 2012 at 08:16:25AM -0800, Keith Packard wrote:
> >> It is never correct to use intel_crtc->bpp in intel_dp_link_required,
> >> so instead pass an explicit bpp in to this function. This patch
> >> only supports 18bpp and 24bpp modes, which means that 10bpc modes will
> >> be computed incorrectly. Fixing that will require more extensive
> >> changes, and so must be addressed separately from this bugfix.
> >>
> >> intel_dp_link_required is called from intel_dp_mode_valid and
> >> intel_dp_mode_fixup.
> >>
> >> * intel_dp_mode_valid is called to list supported modes; in this case,
> >>   the current crtc values cannot be relevant as the modes in question
> >>   may never be selected. Thus, using intel_crtc->bpp is never right.
> >>
> >> * intel_dp_mode_fixup is called during mode setting, but it is run
> >>   well before ironlake_crtc_mode_set is called to set intel_crtc->bpp,
> >>   so using intel_crtc-bpp in this path can only ever get a stale
> >>   value.
> >>
> >> Cc: Lubos Kolouch <lubos.kolouch at gmail.com>
> >> Cc: Adam Jackson <ajax at redhat.com>
> >> Signed-off-by: Keith Packard <keithp at keithp.com>
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=42263
> > Tested-by: camalot at picnicpark.org (Dell Latitude 6510)
> >
> > Not the original reporter and might not exactly be this bug, but likely.
> > -Daniel
> 
> Tested-by: Dave Airlie <airlied at redhat.com>

Another bugzilla for this patch:

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44881
Tested-by: Roland Dreier <roland at digitalvampire.org>

-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48