drm/i915: Ensure that the crtcinfo is populated during mode_fixup()

This should fix the mysterious mode setting failures reported during
boot up and after resume, generally for i8xx class machines.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=16478Reported-and-tested-by: Xavier Chantry <chantry.xavier@gmail.com>
Buzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29413Tested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org

drivers/gpu/drm/i915/intel_display.c

@@ -2463,11 +2463,19 @@ static bool intel_crtc_mode_fixup(struct drm_crtc *crtc,
 				  struct drm_display_mode *adjusted_mode)
 {
 	struct drm_device *dev = crtc->dev;
+
 	if (HAS_PCH_SPLIT(dev)) {
 		/* FDI link clock is fixed at 2.7G */
 		if (mode->clock * 3 > IRONLAKE_FDI_FREQ * 4)
 			return false;
 	}
+
+	/* XXX some encoders set the crtcinfo, others don't.
+	 * Obviously we need some form of conflict resolution here...
+	 */
+	if (adjusted_mode->crtc_htotal == 0)
+		drm_mode_set_crtcinfo(adjusted_mode, 0);
+
 	return true;
 }