diff options
| author | Thierry Reding <treding@nvidia.com> | 2019-10-21 16:34:31 +0200 |
|---|---|---|
| committer | Thierry Reding <treding@nvidia.com> | 2019-10-23 18:18:48 +0200 |
| commit | 79465e0ffeb9e4866939ea562bc55367be91e595 (patch) | |
| tree | 84e20609ed7493c27832f228c01cc016c352243f /drivers/gpu/drm/drm_dp_helper.c | |
| parent | drm/dp: Do not busy-loop during link training (diff) | |
| download | linux-79465e0ffeb9e4866939ea562bc55367be91e595.tar.xz linux-79465e0ffeb9e4866939ea562bc55367be91e595.zip | |
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
Diffstat (limited to 'drivers/gpu/drm/drm_dp_helper.c')
| -rw-r--r-- | drivers/gpu/drm/drm_dp_helper.c | 10 |
1 files changed, 10 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] & |