[PATCH AUTOSEL 6.4 13/31] drm/amd/display: Fix underflow issue on 175hz timing

Sasha Levin
2023-09-08T19:34:32Z

From: Leo Ma <hanghong.ma@amd.com>

[ Upstream commit 735688eb905db529efea0c78466fccc1461c3fde ]

[Why]
Screen underflows happen on 175hz timing for 3 plane overlay case.

[How]
Based on dst y prefetch value clamp to equ or oto for bandwidth
calculation.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Leo Ma <hanghong.ma@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../amd/display/dc/dml/dcn32/display_mode_vba_util_32.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
index 61cc4904ade41..4c645854b263b 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
@@ -3463,6 +3463,7 @@ bool dml32_CalculatePrefetchSchedule(
double TimeForFetchingMetaPTE = 0;
double TimeForFetchingRowInVBlank = 0;
double LinesToRequestPrefetchPixelData = 0;
+ double LinesForPrefetchBandwidth = 0;
unsigned int HostVMDynamicLevelsTrips;
double trip_to_mem;
double Tvm_trips;
@@ -3892,11 +3893,15 @@ bool dml32_CalculatePrefetchSchedule(
TimeForFetchingMetaPTE = Tvm_oto;
TimeForFetchingRowInVBlank = Tr0_oto;
*PrefetchBandwidth = prefetch_bw_oto;
+ /* Clamp to oto for bandwidth calculation */
+ LinesForPrefetchBandwidth = dst_y_prefetch_oto;
} else {
*DestinationLinesForPrefetch = dst_y_prefetch_equ;
TimeForFetchingMetaPTE = Tvm_equ;
TimeForFetchingRowInVBlank = Tr0_equ;
*PrefetchBandwidth = prefetch_bw_equ;
+ /* Clamp to equ for bandwidth calculation */
+ LinesForPrefetchBandwidth = dst_y_prefetch_equ;
}

*DestinationLinesToRequestVMInVBlank = dml_ceil(4.0 * TimeForFetchingMetaPTE / LineTime, 1.0) / 4.0;
@@ -3904,7 +3909,7 @@ bool dml32_CalculatePrefetchSchedule(
*DestinationLinesToRequestRowInVBlank =
dml_ceil(4.0 * TimeForFetchingRowInVBlank / LineTime, 1.0) / 4.0;

- LinesToRequestPrefetchPixelData = *DestinationLinesForPrefetch -
+ LinesToRequestPrefetchPixelData = LinesForPrefetchBandwidth -
*DestinationLinesToRequestVMInVBlank - 2 * *DestinationLinesToRequestRowInVBlank;

#ifdef __DML_VBA_DEBUG__
--
2.40.1