drm/i915: use pipe bpp when setting HDMI bpc

The Intel HDMI encoder can support 8bpc or 12bpc.  Set the appropriate
value based on the pipe bpp when configuring the output.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NKeith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_hdmi.c

@@ -131,6 +131,11 @@ static void intel_hdmi_mode_set(struct drm_encoder *encoder,
 	if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
 		sdvox |= SDVO_HSYNC_ACTIVE_HIGH;
 
+	if (intel_crtc->bpp > 24)
+		sdvox |= COLOR_FORMAT_12bpc;
+	else
+		sdvox |= COLOR_FORMAT_8bpc;
+
 	/* Required on CPT */
 	if (intel_hdmi->has_hdmi_sink && HAS_PCH_CPT(dev))
 		sdvox |= HDMI_MODE_SELECT;