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

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Date:   Mon,  1 Nov 2021 10:17:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Nicholas Kazlauskas <Nicholas.Kazlauskas@....com>,
        Agustin Gutierrez Sanchez <agustin.gutierrez@....com>,
        Eric Yang <Eric.Yang2@....com>,
        Daniel Wheeler <daniel.wheeler@....com>,
        Alex Deucher <alexander.deucher@....com>
Subject: [PATCH 5.14 052/125] drm/amd/display: increase Z9 latency to workaround underflow in Z9

From: Eric Yang <Eric.Yang2@....com>

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@....com>
Acked-by: Agustin Gutierrez Sanchez <agustin.gutierrez@....com>
Signed-off-by: Eric Yang <Eric.Yang2@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Cc: stable@...r.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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,