[PATCH] drm/amd/display: Fix stale replay_events after mod_power stream removal

[Simon Polack <spolack+git@mailbox.org>]

[Why]
mod_power_remove_stream() shifts the remaining power_entity slots down
but does not move replay_events, and mod_power_add_stream() does not
initialize it. replay_events therefore stay bound to the map slot
instead of the stream.

When several streams are disabled in one atomic commit,
amdgpu_dm_mod_power_update_streams() removes them one after another.
The eDP stream can then be looked up in a slot whose stale
replay_events already have replay_event_hw_programming set, so
amdgpu_dm_replay_set_event() returns early ("already in desired state")
without calling mod_power_set_replay_event(). Replay is not disabled
before the eDP panel is powered off. After DPMS on, the sink reports
neither replay state nor frame lock (DPCD 0x378 = 0x00, no error bits),
so the HPD IRQ recovery does not trigger and the panel stays black
until a full modeset.

Seen with an eDP panel using FreeSync Replay plus two DP-MST displays:
DPMS off/on of all outputs leaves eDP black, while DPMS of eDP alone
works. Doing an eDP-only DPMS first makes the next all-output DPMS
fail reliably.

[How]
Shift replay_events together with the PSR cached fields in
mod_power_remove_stream() and initialize it to replay_event_vsync in
mod_power_add_stream(), matching the psr_event_vsync initial value used
for PSR (both vsync events are driven together by
amdgpu_dm_crtc_set_static_screen_optimze()).

Tested on 7.3.0-rc3 (238650ef6c7c): the reproducer above now recovers
reliably, and Replay still engages when the screen is idle.

The issue was debugged with help from an AI assistant (Claude), which
analysed ftrace/kprobe traces and the driver source, pointed to the
missing replay_events handling and suggested this change. I collected
the traces and built and tested the fix on the affected hardware.

Fixes: 4cef2ac4c795 ("drm/amd/display: Introduce power module on Linux")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Simon Polack <spolack+git@mailbox.org>
---
Based on v7.3-rc3 (238650ef6c7c), where it was tested; also applies to
amd-staging-drm-next.

This does not address why stale replay_events can reach the eDP slot
with replay_event_hw_programming already set in the first place; with
per-stream bookkeeping that state is consistent again. Traces
(kprobes/fprobes on the Replay path, eDP-only vs. all-output DPMS) and
DPCD dumps are available on request.

 drivers/gpu/drm/amd/display/modules/power/power.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/modules/power/power.c b/drivers/gpu/drm/amd/display/modules/power/power.c
index 2f9690e65ca9..d900be8cb5fc 100644
--- a/drivers/gpu/drm/amd/display/modules/power/power.c
+++ b/drivers/gpu/drm/amd/display/modules/power/power.c
@@ -328,6 +328,7 @@ bool mod_power_add_stream(struct mod_power *mod_power,
 		core_power->map[core_power->num_entities].psr_enabled = 0;
 		core_power->map[core_power->num_entities].psr_events = psr_event_vsync;
 		core_power->map[core_power->num_entities].psr_power_opt = 0;
+		core_power->map[core_power->num_entities].replay_events = replay_event_vsync;
 		core_power->num_entities++;
 		return true;
 	}
@@ -387,6 +388,7 @@ bool mod_power_remove_stream(struct mod_power *mod_power,
 		core_power->map[i].psr_enabled = core_power->map[i + 1].psr_enabled;
 		core_power->map[i].psr_events = core_power->map[i + 1].psr_events;
 		core_power->map[i].psr_power_opt = core_power->map[i + 1].psr_power_opt;
+		core_power->map[i].replay_events = core_power->map[i + 1].replay_events;
 
 		memcpy(core_power->map[i].psr_context, core_power->map[i + 1].psr_context, sizeof(struct mod_power_psr_context));
 		memset(core_power->map[i + 1].psr_context, 0, sizeof(struct mod_power_psr_context));

base-commit: 238650ef6c7c7cca08e032527329424c9fbd70e5
-- 
2.55.0