drm/i915/dp: Add functions to get min/max src input bpc with DSC

Separate out functions for getting maximum and minimum input BPC based
on platforms, when DSC is used.

v2: Use HAS_DSC macro instead of platform check while getting min input
bpc. (Stan)
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230817142459.89764-10-ankit.k.nautiyal@intel.com

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

@@ -1535,6 +1535,18 @@ intel_dp_compute_link_config_wide(struct intel_dp *intel_dp,
 	return -EINVAL;
 }
 
+static
+u8 intel_dp_dsc_max_src_input_bpc(struct drm_i915_private *i915)
+{
+	/* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
+	if (DISPLAY_VER(i915) >= 12)
+		return 12;
+	if (DISPLAY_VER(i915) == 11)
+		return 10;
+
+	return 0;
+}
+
 int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 max_req_bpc)
 {
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
@@ -1542,11 +1554,12 @@ int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 max_req_bpc)
 	u8 dsc_bpc[3] = {0};
 	u8 dsc_max_bpc;
 
-	/* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
-	if (DISPLAY_VER(i915) >= 12)
-		dsc_max_bpc = min_t(u8, 12, max_req_bpc);
-	else
-		dsc_max_bpc = min_t(u8, 10, max_req_bpc);
+	dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
+
+	if (!dsc_max_bpc)
+		return dsc_max_bpc;
+
+	dsc_max_bpc = min_t(u8, dsc_max_bpc, max_req_bpc);
 
 	num_bpc = drm_dp_dsc_sink_supported_input_bpcs(intel_dp->dsc_dpcd,
 						       dsc_bpc);
@@ -1674,6 +1687,13 @@ static bool intel_dp_dsc_supports_format(struct intel_dp *intel_dp,
 	return drm_dp_dsc_sink_supports_format(intel_dp->dsc_dpcd, sink_dsc_format);
 }
 
+static
+u8 intel_dp_dsc_min_src_input_bpc(struct drm_i915_private *i915)
+{
+	/* Min DSC Input BPC for ICL+ is 8 */
+	return HAS_DSC(i915) ? 8 : 0;
+}
+
 int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 				struct intel_crtc_state *pipe_config,
 				struct drm_connector_state *conn_state,
@@ -1707,10 +1727,9 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 		pipe_bpp = pipe_config->pipe_bpp;
 	}
 
-	/* Min Input BPC for ICL+ is 8 */
-	if (pipe_bpp < 8 * 3) {
+	if (pipe_bpp < intel_dp_dsc_min_src_input_bpc(dev_priv) * 3) {
 		drm_dbg_kms(&dev_priv->drm,
-			    "No DSC support for less than 8bpc\n");
+			    "Computed BPC less than min supported by source for DSC\n");
 		return -EINVAL;
 	}