diff options
| author |   Leo (Hanghong) Ma <hanghong.ma@amd.com> | 2019-11-07 16:30:04 -0500 |
|---|---|---|
| committer |   Alex Deucher <alexander.deucher@amd.com> | 2019-12-05 16:29:11 -0500 |
| commit | fa11d3c9425354c4b47e40f34d29c5b0949fe4ce (patch) | |
| tree | a36387aa85568403951f437a9bf6df34f2139bda | |
| parent | drm/amd/display: 3.2.61 (diff) | |
| download | linux-dev-fa11d3c9425354c4b47e40f34d29c5b0949fe4ce.tar.xz linux-dev-fa11d3c9425354c4b47e40f34d29c5b0949fe4ce.zip | |
drm/amd/display: Change the delay time before enabling FEC
[why]
DP spec requires 1000 symbols delay between the end of link training
and enabling FEC in the stream. Currently we are using 1 miliseconds
delay which is not accurate.
[how]
One lane RBR should have the maximum time for transmitting 1000 LL
codes which is 6.173 us. So using 7 microseconds delay instead of
1 miliseconds.
Signed-off-by: Leo (Hanghong) Ma <hanghong.ma@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Nikola Cornij <Nikola.Cornij@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
| -rw-r--r-- | drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c index 537b4dee8f22..b10019106030 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c @@ -3951,7 +3951,14 @@ void dp_set_fec_enable(struct dc_link *link, bool enable) if (link_enc->funcs->fec_set_enable && link->dpcd_caps.fec_cap.bits.FEC_CAPABLE) { if (link->fec_state == dc_link_fec_ready && enable) { - msleep(1); + /* Accord to DP spec, FEC enable sequence can first + * be transmitted anytime after 1000 LL codes have + * been transmitted on the link after link training + * completion. Using 1 lane RBR should have the maximum + * time for transmitting 1000 LL codes which is 6.173 us. + * So use 7 microseconds delay instead. + */ + udelay(7); link_enc->funcs->fec_set_enable(link_enc, true); link->fec_state = dc_link_fec_enabled; } else if (link->fec_state == dc_link_fec_enabled && !enable) { |