From: Thierry Reding treding@nvidia.com
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 p.zabel@pengutronix.de Signed-off-by: Thierry Reding treding@nvidia.com --- drivers/gpu/drm/drm_dp_helper.c | 10 ++++++++++ include/drm/drm_dp_helper.h | 10 ++++++++++ 2 files changed, 20 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 4b66010771fa..de8ff8ddb445 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 int rd_interval = drm_dp_aux_rd_interval(dpcd); diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 6c12de6f7e46..e0b2c03f3cbb 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -608,6 +608,14 @@ # 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) @@ -1121,6 +1129,8 @@ 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