From 6eac4c8bb10302abc0ea0bd1d506c46ec789ce2b Mon Sep 17 00:00:00 2001 From: Damon Ding Date: Fri, 28 Aug 2026 14:51:50 +0800 Subject: drm/dp: Add helper to validate DP lane counts Add a generic helper function drm_dp_lane_count_is_valid() to check if a DisplayPort lane count is valid. According to the DP specification, only 1, 2, or 4 lanes are supported. This helper avoids duplicating DP lane count validation logic across individual DisplayPort drivers. Suggested-by: Luca Ceresoli Reviewed-by: Luca Ceresoli Signed-off-by: Damon Ding Link: https://patch.msgid.link/20260828065153.590802-3-damon.ding@rock-chips.com Signed-off-by: Luca Ceresoli --- include/drm/display/drm_dp_helper.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h index ab16c1be3900..5b05a7fbe174 100644 --- a/include/drm/display/drm_dp_helper.h +++ b/include/drm/display/drm_dp_helper.h @@ -139,6 +139,12 @@ bool drm_dp_as_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_C int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE]); +static inline bool +drm_dp_lane_count_is_valid(int lane_count) +{ + return lane_count == 1 || lane_count == 2 || lane_count == 4; +} + static inline int drm_dp_max_link_rate(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { -- cgit v1.2.3