Issue a AUX write transaction to DPCD DP_TOTAL_LTTPR_CNT (0xf000a) with total number of LTTPR before link training.
v2: Cosmetic changes. [Suraj] Cc: Jouni Högander <[email protected]> Signed-off-by: Animesh Manna <[email protected]> --- .../drm/i915/display/intel_dp_link_training.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c index aad5fe14962f..d694c2474159 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c @@ -1624,6 +1624,20 @@ intel_dp_128b132b_link_train(struct intel_dp *intel_dp, return passed; } +static void intel_dp_update_lttpr_count(struct intel_dp *intel_dp, + int lttpr_count) +{ + /* + * Program only for DP2.1 and return if LTTPR revison is less than 0x20 + * where 0:3 represents minor rev and 4:7 represent major rev + */ + if (!intel_dp_is_edp(intel_dp) || + intel_dp->lttpr_common_caps[0] <= 0x20) + return; + + drm_dp_dpcd_writeb(&intel_dp->aux, DP_TOTAL_LTTPR_CNT, lttpr_count); +} + /** * intel_dp_start_link_train - start link training * @state: Atomic state @@ -1660,6 +1674,8 @@ void intel_dp_start_link_train(struct intel_atomic_state *state, intel_dp_prepare_link_train(intel_dp, crtc_state); + intel_dp_update_lttpr_count(intel_dp, lttpr_count); + if (intel_dp_is_uhbr(crtc_state)) passed = intel_dp_128b132b_link_train(intel_dp, crtc_state, lttpr_count); else -- 2.29.0
