[PATCH 8/8] drm/i915/alpm: Program lttpr count for DP 2.1 alpm

[Animesh Manna <animesh.manna@intel.com>]

Issue a aux write transaction to dpcd 0xf000a with total number of lttpr
before link traning.

Cc: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
---
 .../gpu/drm/i915/display/intel_dp_link_training.c    | 12 ++++++++++++
 1 file changed, 12 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 27f3716bdc1f..b1e3ab3f8efc 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -1623,6 +1623,16 @@ 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)
+{
+	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
@@ -1659,6 +1669,8 @@ 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