drm/i915: add pipe_config->timings_set

Only used by the lvds encoder. Note that we shouldn't do the same
simple conversion with the FORCE_6BPC flag, since that's much better
handled by moving all the pipe_bpc computation around.

This requires that we pass the pipe config around to encoders, so
that they can set special attributes and set constraints. To do so
introduce a new ->compute_config encoder callback, which is called in
stead of the drm crtc helper's ->mode_fixup.

To avoid massive churn all over the codebase we don't want to convert
all existing ->mode_fixup functions. Instead I've opted to convert
them on an as-needed basis (mostly to cut down on rebase conflicts and
to have more freedom to experiment around while developing the
patches).

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1e30909..673d91a 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3987,7 +3987,7 @@
 	/* All interlaced capable intel hw wants timings in frames. Note though
 	 * that intel_lvds_mode_fixup does some funny tricks with the crtc
 	 * timings, so we need to be careful not to clobber these.*/
-	if (!(adjusted_mode->private_flags & INTEL_MODE_CRTC_TIMINGS_SET))
+	if (!pipe_config->timings_set)
 		drm_mode_set_crtcinfo(adjusted_mode, 0);
 
 	/* WaPruneModeWithIncorrectHsyncOffset: Cantiga+ cannot handle modes
@@ -7560,6 +7560,16 @@
 
 		if (&encoder->new_crtc->base != crtc)
 			continue;
+
+		if (encoder->compute_config) {
+			if (!(encoder->compute_config(encoder, pipe_config))) {
+				DRM_DEBUG_KMS("Encoder config failure\n");
+				goto fail;
+			}
+
+			continue;
+		}
+
 		encoder_funcs = encoder->base.helper_private;
 		if (!(encoder_funcs->mode_fixup(&encoder->base,
 						&pipe_config->requested_mode,