drm/i915/hdmi: Clean up TMDS clock limit exceeding user mode handling

Currently we just use all the hdmi_deep_color_possible() stuff
to compute whether deep color is possible, and leave the 8bpc
case to do its own thing. That doesn't mesh super well with 4:2:0
handling because we might end up going for 8bpc RGB without
considering that it's essentially illegal and we could instead
go for a legal 4:2:0 config.

So let's run through all the clock checks even for 8bpc first.
If we've fully exhausted all options only then do we re-run
the computation for 8bpc while ignoring the downstream TMDS
clock limits. This will guarantee that if there's a config
that respects all limits we will find it, and if there is not
we still allow the user to override the mode manually.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211015133921.4609-7-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index f4feeaf5ce4a..c94ad95442b3 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1166,14 +1166,13 @@ static bool intel_dp_hdmi_tmds_clock_valid(struct intel_dp *intel_dp,
 	return true;
 }
 
-static bool intel_dp_hdmi_deep_color_possible(struct intel_dp *intel_dp,
-					      const struct intel_crtc_state *crtc_state,
-					      int bpc)
+static bool intel_dp_hdmi_bpc_possible(struct intel_dp *intel_dp,
+				       const struct intel_crtc_state *crtc_state,
+				       int bpc)
 {
 
-	return intel_hdmi_deep_color_possible(crtc_state, bpc,
-					      intel_dp->has_hdmi_sink,
-					      intel_dp_hdmi_ycbcr420(intel_dp, crtc_state)) &&
+	return intel_hdmi_bpc_possible(crtc_state, bpc, intel_dp->has_hdmi_sink,
+				       intel_dp_hdmi_ycbcr420(intel_dp, crtc_state)) &&
 		intel_dp_hdmi_tmds_clock_valid(intel_dp, crtc_state, bpc);
 }
 
@@ -1191,7 +1190,7 @@ static int intel_dp_max_bpp(struct intel_dp *intel_dp,
 
 	if (intel_dp->dfp.min_tmds_clock) {
 		for (; bpc >= 10; bpc -= 2) {
-			if (intel_dp_hdmi_deep_color_possible(intel_dp, crtc_state, bpc))
+			if (intel_dp_hdmi_bpc_possible(intel_dp, crtc_state, bpc))
 				break;
 		}
 	}