From fc58a25e03e6f56115fda22aab113533d1932c93 Mon Sep 17 00:00:00 2001 From: Nikola Cornij Date: Mon, 11 Nov 2019 18:03:59 -0500 Subject: [PATCH 4689/4736] drm/amd/display: Reset steer fifo before unblanking the stream [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 Reviewed-by: Tony Cheng Acked-by: Leo Li --- .../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 3549c81b20b7..99f33c7ae528 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 @@ -486,15 +486,23 @@ 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); -- 2.17.1