drm/i915/edp: clean up code and comments around eDP DPCD read

Some minor drive-by cleanups.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026142932.17737-2-jani.nikula@intel.com

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 158438b..73b1ed8 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3747,11 +3747,11 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
        if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_DPCD_REV,
                             intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) ==
                             sizeof(intel_dp->edp_dpcd))
-               DRM_DEBUG_KMS("EDP DPCD : %*ph\n", (int) sizeof(intel_dp->edp_dpcd),
+               DRM_DEBUG_KMS("eDP DPCD: %*ph\n", (int) sizeof(intel_dp->edp_dpcd),
                              intel_dp->edp_dpcd);
 
-       /* Intermediate frequency support */
-       if (intel_dp->edp_dpcd[0] >= 0x03) { /* eDp v1.4 or higher */
+       /* Read the eDP 1.4+ supported link rates. */
+       if (intel_dp->edp_dpcd[0] >= DP_EDP_14) {
                __le16 sink_rates[DP_MAX_SUPPORTED_RATES];
                int i;
 
@@ -3775,6 +3775,10 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
                intel_dp->num_sink_rates = i;
        }
 
+       /*
+        * Use DP_LINK_RATE_SET if DP_SUPPORTED_LINK_RATES are available,
+        * default to DP_MAX_LINK_RATE and DP_LINK_BW_SET otherwise.
+        */
        if (intel_dp->num_sink_rates)
                intel_dp->use_rate_select = true;
        else