[Intel-gfx] [PATCH v5] drm/i915/icl: Set GCP_COLOR_INDICATION only for 10/12 bit deep color

[Aditya Swarup]

From: Clinton Taylor <Clinton.A.Taylor at intel.com>

v2: Fix commit msg to reflect why issue occurs(Jani)
Set GCP_COLOR_INDICATION only when we set 10/12 bit deep color.

Changing settings from 10/12 bit deep color to 8 bit(& vice versa)
doesn't work correctly using xrandr max bpc property. When we
connect a monitor which supports deep color, the highest deep color
setting is selected; which sets GCP_COLOR_INDICATION. When we change
the setting to 8 bit color, we still set GCP_COLOR_INDICATION which
doesn't allow the switch back to 8 bit color.

v3,4: Add comments & drop changes in intel_hdmi_compute_config(Ville)
Since HSW+, GCP_COLOR_INDICATION is not required for 8bpc.

Drop the changes in intel_hdmi_compute_config as desired_bpp
is needed to change values for pipe_bpp based on bw_constrained flag.

v5: Fix missing logical && in condition for setting GCP_COLOR_INDICATION.

Signed-off-by: Clinton Taylor <Clinton.A.Taylor at intel.com>
Signed-off-by: Aditya Swarup <aditya.swarup at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>
Cc: Manasi Navare <manasi.d.navare at intel.com>
---
I tested the patch and there is still a bug in setting 10 bit deep
color mode. I am unable to set 10 bit color from xrandr from 12 bit
deep color or 8 bit. 
 drivers/gpu/drm/i915/intel_hdmi.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 5ccb305a6e1c..d550653ad29f 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -962,8 +962,12 @@ static void intel_hdmi_compute_gcp_infoframe(struct intel_encoder *encoder,
 	crtc_state->infoframes.enable |=
 		intel_hdmi_infoframe_enable(HDMI_PACKET_TYPE_GENERAL_CONTROL);
 
-	/* Indicate color depth whenever the sink supports deep color */
-	if (hdmi_sink_is_deep_color(conn_state))
+	/* Indicate color depth whenever the sink supports deep color
+	 * Also, 8bpc + color depth indication is no longer supported
+	 * for HSW+ platforms.
+	 * */
+	if (hdmi_sink_is_deep_color(conn_state) &&
+	    crtc_state->pipe_bpp > 24)
 		crtc_state->infoframes.gcp |= GCP_COLOR_INDICATION;
 
 	/* Enable default_phase whenever the display mode is suitably aligned */
-- 
2.17.1