[Intel-gfx] [PATCH] drm/i915/dp: Fix eDP max rate for display 11+

[Jani Nikula]

From: Matt Atwood <matthew.s.atwood at intel.com>

intel_dp_set_source_rates() calls intel_dp_is_edp(), which is unsafe to
use before intel_encoder->type is set. This causes incorrect max source
rate to be used for display 11+. On EHL and JSL, HBR3 is used instead of
HBR2, and on the other affected platforms, HBR2 is used instead of HBR3.

Move intel_dp_set_source_rates() to after intel_encoder->type is
set. Add comment to intel_dp_is_edp() describing unsafe usages. Cleanup
intel_dp_init_connector() while at it.

Note: The same change was originally added as commit 680c45c767f6
("drm/i915/dp: Correctly advertise HBR3 for GEN11+"), but later reverted
due to issues in CI in commit d3913019602e ("Revert "drm/i915/dp:
Correctly advertise HBR3 for GEN11+"").

v2: Alter intel_dp_set_source_rates final position (Ville/Manasi).
    Remove outdated comment (Ville).
    Slight optimization of control flow in intel_dp_init_connector.
    Slight rewording in commit message.

Cc: Uma Shankar <uma.shankar at intel.com>
Signed-off-by: Matt Atwood <matthew.s.atwood at intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
[Jani: Expand on the commit message.]
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 28 ++++++++++---------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 6cc03b9e4321..41130aa4b191 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -100,6 +100,8 @@ static const u8 valid_dsc_slicecount[] = {1, 2, 4};
  *
  * If a CPU or PCH DP output is attached to an eDP panel, this function
  * will return true, and false otherwise.
+ *
+ * This function is not safe to use prior to encoder type being set.
  */
 bool intel_dp_is_edp(struct intel_dp *intel_dp)
 {
@@ -5301,8 +5303,6 @@ intel_dp_init_connector(struct intel_digital_port *dig_port,
 		     intel_encoder->base.name))
 		return false;
 
-	intel_dp_set_source_rates(intel_dp);
-
 	intel_dp->reset_link_params = true;
 	intel_dp->pps.pps_pipe = INVALID_PIPE;
 	intel_dp->pps.active_pipe = INVALID_PIPE;
@@ -5318,28 +5318,22 @@ intel_dp_init_connector(struct intel_digital_port *dig_port,
 		 */
 		drm_WARN_ON(dev, intel_phy_is_tc(dev_priv, phy));
 		type = DRM_MODE_CONNECTOR_eDP;
+		intel_encoder->type = INTEL_OUTPUT_EDP;
+
+		/* eDP only on port B and/or C on vlv/chv */
+		if (drm_WARN_ON(dev, (IS_VALLEYVIEW(dev_priv) ||
+				      IS_CHERRYVIEW(dev_priv)) &&
+				port != PORT_B && port != PORT_C))
+			return false;
 	} else {
 		type = DRM_MODE_CONNECTOR_DisplayPort;
 	}
 
+	intel_dp_set_source_rates(intel_dp);
+
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
 		intel_dp->pps.active_pipe = vlv_active_pipe(intel_dp);
 
-	/*
-	 * For eDP we always set the encoder type to INTEL_OUTPUT_EDP, but
-	 * for DP the encoder type can be set by the caller to
-	 * INTEL_OUTPUT_UNKNOWN for DDI, so don't rewrite it.
-	 */
-	if (type == DRM_MODE_CONNECTOR_eDP)
-		intel_encoder->type = INTEL_OUTPUT_EDP;
-
-	/* eDP only on port B and/or C on vlv/chv */
-	if (drm_WARN_ON(dev, (IS_VALLEYVIEW(dev_priv) ||
-			      IS_CHERRYVIEW(dev_priv)) &&
-			intel_dp_is_edp(intel_dp) &&
-			port != PORT_B && port != PORT_C))
-		return false;
-
 	drm_dbg_kms(&dev_priv->drm,
 		    "Adding %s connector on [ENCODER:%d:%s]\n",
 		    type == DRM_MODE_CONNECTOR_eDP ? "eDP" : "DP",
-- 
2.20.1