[Intel-gfx] [PATCH 1/2] drm/i915: Check lane count when determining FEC support

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

ICL doesn't support FEC with a x1 DP link. Make sure
we don't try to enable FEC in such cases.

Requires a bit of reordering to make sure we've computed lane_count
before checking it.

Cc: Luca Coelho <luciano.coelho at intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 55ba6eeaa810..2cde8ac513bb 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1363,7 +1363,8 @@ static bool intel_dp_source_supports_fec(struct intel_dp *intel_dp,
 	if (DISPLAY_VER(dev_priv) >= 12)
 		return true;
 
-	if (DISPLAY_VER(dev_priv) == 11 && encoder->port != PORT_A)
+	if (DISPLAY_VER(dev_priv) == 11 &&
+	    encoder->port != PORT_A && pipe_config->lane_count != 1)
 		return true;
 
 	return false;
@@ -2105,15 +2106,6 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 		&pipe_config->hw.adjusted_mode;
 	int ret;
 
-	pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
-		intel_dp_supports_fec(intel_dp, pipe_config);
-
-	if (!intel_dp_supports_dsc(intel_dp, pipe_config))
-		return -EINVAL;
-
-	if (!intel_dp_dsc_supports_format(intel_dp, pipe_config->output_format))
-		return -EINVAL;
-
 	/*
 	 * compute pipe bpp is set to false for DP MST DSC case
 	 * and compressed_bpp is calculated same time once
@@ -2134,6 +2126,15 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
 		}
 	}
 
+	pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
+		intel_dp_supports_fec(intel_dp, pipe_config);
+
+	if (!intel_dp_supports_dsc(intel_dp, pipe_config))
+		return -EINVAL;
+
+	if (!intel_dp_dsc_supports_format(intel_dp, pipe_config->output_format))
+		return -EINVAL;
+
 	/* Calculate Slice count */
 	if (intel_dp_is_edp(intel_dp)) {
 		pipe_config->dsc.slice_count =
-- 
2.41.0