drm/dp: Add drm_dp_fast_training_cap() helper

Add a helper that checks for the fast training capability given the DPCD
receiver capabilities blob.

Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191021143437.1477719-4-thierry.reding@gmail.com

diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index e0e76f7634a94549a0c953ab6842d3f6d5506eba..1179d3f2ba7c11f8c2bb3eeab0aab108b02def89 100644 (file)
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1215,6 +1215,13 @@ drm_dp_enhanced_frame_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
                (dpcd[DP_MAX_LANE_COUNT] & DP_ENHANCED_FRAME_CAP);
 }
 
+static inline bool
+drm_dp_fast_training_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+       return dpcd[DP_DPCD_REV] >= 0x11 &&
+               (dpcd[DP_MAX_DOWNSPREAD] & DP_NO_AUX_HANDSHAKE_LINK_TRAINING);
+}
+
 static inline bool
 drm_dp_tps3_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 {