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 <p.zabel@pengutronix.de>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191021143437.1477719-8-thierry.reding@gmail.com
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index b3402cb..04f6c0b 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