diff options
| author | Thierry Reding <[email protected]> | 2019-10-21 16:34:31 +0200 |
|---|---|---|
| committer | Thierry Reding <[email protected]> | 2019-10-23 18:18:48 +0200 |
| commit | 79465e0ffeb9e4866939ea562bc55367be91e595 (patch) | |
| tree | 84e20609ed7493c27832f228c01cc016c352243f | |
| parent | fc6b42045e51a8e2793751e03daa39dc99c25983 (diff) | |
drm/dp: Add helper to get post-cursor adjustments
If the transmitter supports pre-emphasis post cursor2 the sink will
request adjustments in a similar way to how it requests adjustments to
the voltage swing and pre-emphasis settings.
Add a helper to extract these adjustments on a per-lane basis from the
DPCD link status.
Reviewed-by: Philipp Zabel <[email protected]>
Reviewed-by: Lyude Paul <[email protected]>
Signed-off-by: Thierry Reding <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
| -rw-r--r-- | drivers/gpu/drm/drm_dp_helper.c | 10 | ||||
| -rw-r--r-- | include/drm/drm_dp_helper.h | 10 |
2 files changed, 20 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index ac802b04f120..f567141aff54 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -120,6 +120,16 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI } EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis); +u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE], + unsigned int lane) +{ + unsigned int offset = DP_ADJUST_REQUEST_POST_CURSOR2; + u8 value = dp_link_status(link_status, offset); + + return (value >> (lane << 1)) & 0x3; +} +EXPORT_SYMBOL(drm_dp_get_adjust_request_post_cursor); + void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { unsigned long rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] & diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index b3402cb186a4..04f6c0bb0274 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -605,6 +605,14 @@ # define DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT 6 #define DP_ADJUST_REQUEST_POST_CURSOR2 0x20c +# define DP_ADJUST_POST_CURSOR2_LANE0_MASK 0x03 +# define DP_ADJUST_POST_CURSOR2_LANE0_SHIFT 0 +# define DP_ADJUST_POST_CURSOR2_LANE1_MASK 0x0c +# define DP_ADJUST_POST_CURSOR2_LANE1_SHIFT 2 +# define DP_ADJUST_POST_CURSOR2_LANE2_MASK 0x30 +# define DP_ADJUST_POST_CURSOR2_LANE2_SHIFT 4 +# define DP_ADJUST_POST_CURSOR2_LANE3_MASK 0xc0 +# define DP_ADJUST_POST_CURSOR2_LANE3_SHIFT 6 #define DP_TEST_REQUEST 0x218 # define DP_TEST_LINK_TRAINING (1 << 0) @@ -1122,6 +1130,8 @@ 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], int lane); +u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE], + unsigned int lane); #define DP_BRANCH_OUI_HEADER_SIZE 0xc #define DP_RECEIVER_CAP_SIZE 0xf |