[PATCH 5.14 052/125] drm/amd/display: increase Z9 latency to workaround underflow in Z9

From: Greg Kroah-Hartman
Date: Mon Nov 01 2021 - 05:45:35 EST


From: Eric Yang <Eric.Yang2@xxxxxxx>

commit 4835ea6c173a8d8dfbfdbb21c4cd987d12681610 upstream.

[Why]
Z9 latency is higher than when we originally tuned the watermark
parameters, causing underflow. Increasing the value until the latency
issues is resolved.

Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@xxxxxxx>
Acked-by: Agustin Gutierrez Sanchez <agustin.gutierrez@xxxxxxx>
Signed-off-by: Eric Yang <Eric.Yang2@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn31/dcn31_resource.c
@@ -217,8 +217,8 @@ struct _vcs_dpi_soc_bounding_box_st dcn3
.num_states = 5,
.sr_exit_time_us = 9.0,
.sr_enter_plus_exit_time_us = 11.0,
- .sr_exit_z8_time_us = 402.0,
- .sr_enter_plus_exit_z8_time_us = 520.0,
+ .sr_exit_z8_time_us = 442.0,
+ .sr_enter_plus_exit_z8_time_us = 560.0,
.writeback_latency_us = 12.0,
.dram_channel_width_bytes = 4,
.round_trip_ping_latency_dcfclk_cycles = 106,