drm/i915: Limit Valleyview and earlier to only using mappable scanout
Valleyview appears to be limited to only scanning out from the first 512MiB of the Global GTT. Lets presume that this behaviour was inherited from the display block copied from g4x (not Ironlake) and all earlier generations are similarly affected, though testing suggests different symptoms. For simplicity, impose that these platforms must scanout from the mappable region. (For extra simplicity, use HAS_GMCH_DISPLAY even though this catches Cherryview which does not appear to be limited to the low aperture for its scanout.) v2: Use HAS_GMCH_DISPLAY() to more clearly convey my intent about limiting this workaround to the old style of display engine. v3: Update changelog to reflect testing by Ville Syrjälä v4: Include the changes to the comments as well Reported-by:Luis Botello <luis.botello.ortega@intel.com> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98036 Fixes: 2efb813d ("drm/i915: Fallback to using unmappable memory for scanout") Signed-off-by:
Chris Wilson <chris@chris-wilson.co.uk> Cc: Akash Goel <akash.goel@intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.9-rc1+ Link: http://patchwork.freedesktop.org/patch/msgid/20161107110128.28762-1-chris@chris-wilson.co.uk Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com
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