From: Nikola Cornij nikola.cornij@amd.com
[ Upstream commit 87de6cb2f28153bc74d0a001ca099c29453e145f ]
[why] During mode transition steer fifo could overflow. Quite often it recovers by itself, but sometimes it doesn't.
[how] Add steer fifo reset before unblanking the stream. Also add a short delay when resetting dig resync fifo to make sure register writes don't end up back-to-back, in which case the HW might miss the reset request.
Signed-off-by: Nikola Cornij nikola.cornij@amd.com Reviewed-by: Tony Cheng Tony.Cheng@amd.com Acked-by: Leo Li sunpeng.li@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- .../drm/amd/display/dc/dcn20/dcn20_stream_encoder.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_stream_encoder.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_stream_encoder.c index 5ab9d6240498..e95025b1d14d 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_stream_encoder.c +++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_stream_encoder.c @@ -492,15 +492,23 @@ void enc2_stream_encoder_dp_unblank( DP_VID_N_MUL, n_multiply); }
- /* set DIG_START to 0x1 to reset FIFO */ + /* make sure stream is disabled before resetting steer fifo */ + REG_UPDATE(DP_VID_STREAM_CNTL, DP_VID_STREAM_ENABLE, false); + REG_WAIT(DP_VID_STREAM_CNTL, DP_VID_STREAM_STATUS, 0, 10, 5000);
+ /* set DIG_START to 0x1 to reset FIFO */ REG_UPDATE(DIG_FE_CNTL, DIG_START, 1); + udelay(1);
/* write 0 to take the FIFO out of reset */
REG_UPDATE(DIG_FE_CNTL, DIG_START, 0);
- /* switch DP encoder to CRTC data */ + /* switch DP encoder to CRTC data, but reset it the fifo first. It may happen + * that it overflows during mode transition, and sometimes doesn't recover. + */ + REG_UPDATE(DP_STEER_FIFO, DP_STEER_FIFO_RESET, 1); + udelay(10);
REG_UPDATE(DP_STEER_FIFO, DP_STEER_FIFO_RESET, 0);