[PATCH 1/9] drm/i915/dp: Check if force dsc bpc <= max requested bpc

[Ankit Nautiyal]

Add a check to use force DSC bpc only if its less that the connector max
requested bpc.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 7400d6b4c587..5b555951cda5 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1473,7 +1473,7 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
 	const struct drm_display_mode *adjusted_mode =
 		&pipe_config->hw.adjusted_mode;
-	int pipe_bpp;
+	int pipe_bpp, pipe_bpp_max;
 	int ret;
 
 	pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
@@ -1482,11 +1482,22 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 	if (!intel_dp_supports_dsc(intel_dp, pipe_config))
 		return -EINVAL;
 
-	pipe_bpp = intel_dp_dsc_compute_bpp(intel_dp, conn_state->max_requested_bpc);
+	/*
+	 * If Force DSC BPC is set, try to use that to compute the pipe bpp,
+	 * otherwise set pipe_bpp to the max bpp.
+	 */
+	pipe_bpp_max = intel_dp_dsc_compute_bpp(intel_dp, conn_state->max_requested_bpc);
 
-	if (intel_dp->force_dsc_bpc) {
+	if (intel_dp->force_dsc_bpc &&
+	    intel_dp->force_dsc_bpc <= conn_state->max_requested_bpc) {
 		pipe_bpp = intel_dp->force_dsc_bpc * 3;
 		drm_dbg_kms(&dev_priv->drm, "Input DSC BPP forced to %d", pipe_bpp);
+	} else if (intel_dp->force_dsc_bpc < conn_state->max_requested_bpc) {
+		drm_dbg_kms(&dev_priv->drm, "Ignoring force dsc bpc:%d, conflict with max requested bpc:%d",
+			    intel_dp->force_dsc_bpc, conn_state->max_requested_bpc);
+		pipe_bpp = pipe_bpp_max;
+	} else {
+		pipe_bpp = pipe_bpp_max;
 	}
 
 	/* Min Input BPC for ICL+ is 8 */
@@ -1496,12 +1507,13 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 		return -EINVAL;
 	}
 
+	pipe_config->pipe_bpp = pipe_bpp;
+
 	/*
-	 * For now enable DSC for max bpp, max link rate, max lane count.
+	 * For now enable DSC for max link rate, max lane count.
 	 * Optimize this later for the minimum possible link rate/lane count
 	 * with DSC enabled for the requested mode.
 	 */
-	pipe_config->pipe_bpp = pipe_bpp;
 	pipe_config->port_clock = limits->max_rate;
 	pipe_config->lane_count = limits->max_lane_count;
 
-- 
2.25.1