[PATCH AUTOSEL 5.2 19/76] drm/amd/display: fix DMCU hang when going into Modern Standby

From: Sasha Levin
Date: Fri Aug 02 2019 - 09:20:31 EST


From: Zi Yu Liao <ziyu.liao@xxxxxxx>

[ Upstream commit 1ca068ed34d6b39d336c1b0d618ed73ba8f04548 ]

[why]
When the system is going into suspend, set_backlight gets called
after the eDP got blanked. Since smooth brightness is enabled,
the driver will make a call into the DMCU to ramp the brightness.
The DMCU would try to enable ABM to do so. But since the display is
blanked, this ends up causing ABM1_ACE_DBUF_REG_UPDATE_PENDING to
get stuck at 1, which results in a dead lock in the DMCU firmware.

[how]
Disable brightness ramping when the eDP display is blanked.

Signed-off-by: Zi Yu Liao <ziyu.liao@xxxxxxx>
Reviewed-by: Eric Yang <eric.yang2@xxxxxxx>
Acked-by: Anthony Koo <Anthony.Koo@xxxxxxx>
Acked-by: Leo Li <sunpeng.li@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/amd/display/dc/core/dc_link.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index a3ff33ff6da16..adf39e3b8d29d 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -2284,7 +2284,7 @@ bool dc_link_set_backlight_level(const struct dc_link *link,
if (core_dc->current_state->res_ctx.pipe_ctx[i].stream) {
if (core_dc->current_state->res_ctx.
pipe_ctx[i].stream->link
- == link)
+ == link) {
/* DMCU -1 for all controller id values,
* therefore +1 here
*/
@@ -2292,6 +2292,13 @@ bool dc_link_set_backlight_level(const struct dc_link *link,
core_dc->current_state->
res_ctx.pipe_ctx[i].stream_res.tg->inst +
1;
+
+ /* Disable brightness ramping when the display is blanked
+ * as it can hang the DMCU
+ */
+ if (core_dc->current_state->res_ctx.pipe_ctx[i].plane_state == NULL)
+ frame_ramp = 0;
+ }
}
}
abm->funcs->set_backlight_level_pwm(
--
2.20.1