drm/i915/dp: Fail state computation for invalid DSC source input BPP values

There is no reason to accept an invalid minimum/maximum DSC source input
BPP value (i.e a minimum DSC input BPP value above the maximum pipe BPP
or a maximum DSC input BPP value below the minimum pipe BPP value), fail
the state computation in these cases.

Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251215192357.172201-17-imre.deak@intel.com

Author: ideak

drivers/gpu/drm/i915/display/intel_dp.c

@@ -2661,16 +2661,30 @@ intel_dp_compute_config_link_bpp_limits(struct intel_dp *intel_dp,
 	return true;
 }
 
-static void
-intel_dp_dsc_compute_pipe_bpp_limits(struct intel_dp *intel_dp,
+static bool
+intel_dp_dsc_compute_pipe_bpp_limits(struct intel_connector *connector,
 				     struct link_config_limits *limits)
 {
-	struct intel_display *display = to_intel_display(intel_dp);
+	struct intel_display *display = to_intel_display(connector);
+	const struct link_config_limits orig_limits = *limits;
 	int dsc_min_bpc = intel_dp_dsc_min_src_input_bpc();
 	int dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(display);
 
-	limits->pipe.max_bpp = clamp(limits->pipe.max_bpp, dsc_min_bpc * 3, dsc_max_bpc * 3);
-	limits->pipe.min_bpp = clamp(limits->pipe.min_bpp, dsc_min_bpc * 3, dsc_max_bpc * 3);
+	limits->pipe.min_bpp = max(limits->pipe.min_bpp, dsc_min_bpc * 3);
+	limits->pipe.max_bpp = min(limits->pipe.max_bpp, dsc_max_bpc * 3);
+
+	if (limits->pipe.min_bpp <= 0 ||
+	    limits->pipe.min_bpp > limits->pipe.max_bpp) {
+		drm_dbg_kms(display->drm,
+			    "[CONNECTOR:%d:%s] Invalid DSC src/sink input BPP (src:%d-%d pipe:%d-%d)\n",
+			    connector->base.base.id, connector->base.name,
+			    dsc_min_bpc * 3, dsc_max_bpc * 3,
+			    orig_limits.pipe.min_bpp, orig_limits.pipe.max_bpp);
+
+		return false;
+	}
+
+	return true;
 }
 
 bool
@@ -2710,8 +2724,8 @@ intel_dp_compute_config_limits(struct intel_dp *intel_dp,
 							respect_downstream_limits);
 	}
 
-	if (dsc)
-		intel_dp_dsc_compute_pipe_bpp_limits(intel_dp, limits);
+	if (dsc && !intel_dp_dsc_compute_pipe_bpp_limits(connector, limits))
+		return false;
 
 	if (is_mst || intel_dp->use_max_params) {
 		/*