[PATCH 5/5] drm/i915/dp: Ignore max_requested_bpc if its too low for DSC

[Ankit Nautiyal]

At the moment, while choosing the input bpc for DSC, we take into
account the max_requested_bpc property. This creates a problem, if the
max_requested_bpc is lower than the minimum bpc required by source with
DSC.

So consider max_requested_bpc if its within the limits that we can
support with DSC.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 7e7b08d44f06..32122ea07a95 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1634,6 +1634,16 @@ int intel_dp_dsc_max_src_input_bpc(struct drm_i915_private *i915)
 	return 12;
 }
 
+static int
+intel_dp_dsc_limit_max_bpc(int max_requested_bpc, int src_dsc_max_bpc, int src_dsc_min_bpc)
+{
+	/* Consider max_requested_bpc only if src can support it with DSC */
+	if (max_requested_bpc >= src_dsc_min_bpc)
+		return min(src_dsc_max_bpc, max_requested_bpc);
+
+	return src_dsc_max_bpc;
+}
+
 int intel_dp_dsc_compute_max_bpp(const struct intel_connector *connector,
 				 u8 max_req_bpc)
 {
@@ -1647,7 +1657,8 @@ int intel_dp_dsc_compute_max_bpp(const struct intel_connector *connector,
 	if (!dsc_max_bpc)
 		return dsc_max_bpc;
 
-	dsc_max_bpc = min(dsc_max_bpc, max_req_bpc);
+	dsc_max_bpc = intel_dp_dsc_limit_max_bpc(max_req_bpc, dsc_max_bpc,
+						 intel_dp_dsc_min_src_input_bpc(i915));
 
 	num_bpc = drm_dp_dsc_sink_supported_input_bpcs(connector->dp.dsc_dpcd,
 						       dsc_bpc);
@@ -2035,8 +2046,11 @@ bool is_dsc_pipe_bpp_sufficient(struct drm_i915_private *i915,
 {
 	int dsc_max_bpc, dsc_min_bpc, dsc_max_pipe_bpp, dsc_min_pipe_bpp;
 
-	dsc_max_bpc = min(intel_dp_dsc_max_src_input_bpc(i915), conn_state->max_requested_bpc);
 	dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
+	dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
+
+	dsc_max_bpc = intel_dp_dsc_limit_max_bpc(conn_state->max_requested_bpc,
+						 dsc_max_bpc, dsc_min_bpc);
 
 	dsc_max_pipe_bpp = min(dsc_max_bpc * 3, limits->pipe.max_bpp);
 	dsc_min_pipe_bpp = max(dsc_min_bpc * 3, limits->pipe.min_bpp);
@@ -2096,14 +2110,14 @@ static int intel_dp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
 		}
 	}
 
+	dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
 	dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
 	if (!dsc_max_bpc)
 		return -EINVAL;
 
-	dsc_max_bpc = min(dsc_max_bpc, max_req_bpc);
+	dsc_max_bpc = intel_dp_dsc_limit_max_bpc(max_req_bpc, dsc_max_bpc, dsc_min_bpc);
 	dsc_max_bpp = min(dsc_max_bpc * 3, limits->pipe.max_bpp);
 
-	dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
 	dsc_min_bpp = max(dsc_min_bpc * 3, limits->pipe.min_bpp);
 
 	/*
-- 
2.40.1