drm/dp: Add POST_LT_ADJ_REQ helpers

Add small helpers (drm_dp_post_lt_adj_req_supported() and
drm_dp_post_lt_adj_req_in_progress()) to help with implementing
the POST_LT_ADJ_REQ sequence.

Tested-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250718120154.15492-3-ville.syrjala@linux.intel.com

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 4aaeae4fa03c36cf8697d819fe352e5ff5623f8e..5426db21e53f7d43b3c6615e64369f83135a2b12 100644 (file)
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -123,6 +123,14 @@ bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
 }
 EXPORT_SYMBOL(drm_dp_clock_recovery_ok);
 
+bool drm_dp_post_lt_adj_req_in_progress(const u8 link_status[DP_LINK_STATUS_SIZE])
+{
+       u8 lane_align = dp_link_status(link_status, DP_LANE_ALIGN_STATUS_UPDATED);
+
+       return lane_align & DP_POST_LT_ADJ_REQ_IN_PROGRESS;
+}
+EXPORT_SYMBOL(drm_dp_post_lt_adj_req_in_progress);
+
 u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
                                     int lane)
 {

diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index 87caa4f1fdb866960aa941a624857849d17bdc4a..52ce2809701518d6a9fe5bf21d0133b8f32e717f 100644 (file)
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -37,6 +37,7 @@ bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
                          int lane_count);
 bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
                              int lane_count);
+bool drm_dp_post_lt_adj_req_in_progress(const u8 link_status[DP_LINK_STATUS_SIZE]);
 u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
                                     int lane);
 u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],
@@ -155,6 +156,13 @@ 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_post_lt_adj_req_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+       return dpcd[DP_DPCD_REV] >= 0x13 &&
+               (dpcd[DP_MAX_LANE_COUNT] & DP_POST_LT_ADJ_REQ_SUPPORTED);
+}
+
 static inline bool
 drm_dp_fast_training_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 {