drm/i915: Validate mode against max. link data rate for DP MST

Not validating the mode rate against max. link rate results in not pruning
invalid modes. For e.g, a HBR2 5.4 Gbps 2-lane configuration does not
support 4k@60Hz. But, we do not reject this mode.

So, make use of the helpers in intel_dp to validate mode data rate against
max. link data rate of a configuration.

v3: Renamed local variables again for consistency (Manasi)
v2: Renamed mode data rate local variable to be more explanatory.

Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479243546-17189-1-git-send-email-dhinakaran.pandiyan@intel.com
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index 1f98757f61e7..205fe4748ec5 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -350,7 +350,17 @@ static enum drm_mode_status
 intel_dp_mst_mode_valid(struct drm_connector *connector,
                         struct drm_display_mode *mode)
 {
+        struct intel_connector *intel_connector = to_intel_connector(connector);
+        struct intel_dp *intel_dp = intel_connector->mst_port;
         int max_dotclk = to_i915(connector->dev)->max_dotclk_freq;
+        int bpp = 24; /* MST uses fixed bpp */
+        int max_rate, mode_rate, max_lanes, max_link_clock;
+
+        max_link_clock = intel_dp_max_link_rate(intel_dp);
+        max_lanes = drm_dp_max_lane_count(intel_dp->dpcd);
+
+        max_rate = intel_dp_max_data_rate(max_link_clock, max_lanes);
+        mode_rate = intel_dp_link_required(mode->clock, bpp);
 
         /* TODO - validate mode against available PBN for link */
         if (mode->clock < 10000)
@@ -359,7 +369,7 @@ intel_dp_mst_mode_valid(struct drm_connector *connector,
         if (mode->flags & DRM_MODE_FLAG_DBLCLK)
                 return MODE_H_ILLEGAL;
 
-        if (mode->clock > max_dotclk)
+        if (mode_rate > max_rate || mode->clock > max_dotclk)
                 return MODE_CLOCK_HIGH;
 
         return MODE_OK;