[PATCH AUTOSEL 6.10 078/121] drm/amd/display: Disable DMCUB timeout for DCN35

[Sasha Levin]

From: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>

[ Upstream commit 7c70e60fbf4bff1123f0e8d5cb1ae71df6164d7f ]

[Why]
DMCUB can intermittently take longer than expected to process commands.

Old ASIC policy was to continue while logging a diagnostic error - which
works fine for ASIC without IPS, but with IPS this could lead to a race
condition where we attempt to access DCN state while it's inaccessible,
leading to a system hang when the NIU port is not disabled or register
accesses that timeout and the display configuration in an undefined
state.

[How]
We need to investigate why these accesses take longer than expected, but
for now we should disable the timeout on DCN35 to avoid this race
condition. Since the waits happen only at lower interrupt levels the
risk of taking too long at higher IRQ and causing a system watchdog
timeout are minimal.

Reviewed-by: Ovidiu Bunea <ovidiu.bunea at amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed at amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/gpu/drm/amd/display/dc/resource/dcn35/dcn35_resource.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/display/dc/resource/dcn35/dcn35_resource.c b/drivers/gpu/drm/amd/display/dc/resource/dcn35/dcn35_resource.c
index 28c4599076989..915d68cc04e9c 100644
--- a/drivers/gpu/drm/amd/display/dc/resource/dcn35/dcn35_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/resource/dcn35/dcn35_resource.c
@@ -785,6 +785,7 @@ static const struct dc_debug_options debug_defaults_drv = {
 	.ips2_entry_delay_us = 800,
 	.disable_dmub_reallow_idle = false,
 	.static_screen_wait_frames = 2,
+	.disable_timeout = true,
 };
 
 static const struct dc_panel_config panel_config_defaults = {
-- 
2.43.0