[Intel-gfx] [PATCH v8] 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.

v6: Fix comment formatting (Ville)

v7: Add reviewed by Ville

v8: Set GCP_COLOR_INDICATION based on spec:
For Gen 7.5 or later platforms, indicate color depth only for deep
color modes. Bspec: 8135,7751,50524

Pre DDI platforms, indicate color depth if deep color is supported
by sink. Bspec: 7854

Exception: CHERRYVIEW behaves like Pre DDI platforms.
Bspec: 15975

Check pipe_bpp is less than bpp * 3 in hdmi_deep_color_possible,
to not set 12 bit deep color for every modeset. This fixes the issue
where 12 bit color was selected even when user selected 10 bit.(Ville)

Co-Developed-by: Aditya Swarup <aditya.swarup at intel.com>
Co-Developed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
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>
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_hdmi.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index e1005d7b75fd..620bc89e2120 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -973,9 +973,18 @@ 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))
-		crtc_state->infoframes.gcp |= GCP_COLOR_INDICATION;
+	/* Indicate color depth whenever the sink supports deep color:
+	 * For Gen 7.5 or later platforms, indicate color depth only for deep
+	 * color modes.
+	 * Pre DDI platforms, indicate color depth if deep color is supported
+	 * by sink.
+	 * Exception: CHERRYVIEW behaves like Pre DDI platforms.
+	 */
+	if (hdmi_sink_is_deep_color(conn_state)) {
+		if(!HAS_DDI(dev_priv) || IS_CHERRYVIEW(dev_priv) ||
+		   crtc_state->pipe_bpp > 24)
+			crtc_state->infoframes.gcp |= GCP_COLOR_INDICATION;
+	}
 
 	/* Enable default_phase whenever the display mode is suitably aligned */
 	if (gcp_default_phase_possible(crtc_state->pipe_bpp,
@@ -2172,7 +2181,7 @@ static bool hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
 	if (bpc == 10 && INTEL_GEN(dev_priv) < 11)
 		return false;
 
-	if (crtc_state->pipe_bpp <= 8*3)
+	if (crtc_state->pipe_bpp < bpc*3)
 		return false;
 
 	if (!crtc_state->has_hdmi_sink)
-- 
2.17.1