On 1/23/2026 12:07 PM, Hogander, Jouni wrote:
On Fri, 2026-01-23 at 10:42 +0530, Nautiyal, Ankit K wrote:
On 12/23/2025 4:21 PM, Jouni Högander wrote:
We are planning to move using trans push mechanism to trigger the
Frame
Change event. in that case we can't wait PSR to idle before send
Typo: s/in/In
push
happens. Due to this move wait for idle to be done after possible
send push
is done.
This should be ok for Frame Change event triggered by register
write as
well. Wait for idle is needed only for corner case where PSR is
transitioning into DEEP_SLEEP when Frame Change event is triggered.
It just
has to be before wait for vblank. Otherwise we may have vblank
before PSR
enters DEEP_SLEEP and still using old frame buffers for first frame
after
wake up.
Signed-off-by: Jouni Högander <[email protected]>
---
drivers/gpu/drm/i915/display/intel_display.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_display.c
b/drivers/gpu/drm/i915/display/intel_display.c
index c7ca4f53b8b8..1aca4802b7d5 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7333,9 +7333,6 @@ static void intel_atomic_dsb_finish(struct
intel_atomic_state *state,
intel_psr_trigger_frame_change_event(new_crtc_stat
e->dsb_commit,
state, crtc);
- intel_psr_wait_for_idle_dsb(new_crtc_state-
dsb_commit,
- new_crtc_state);
-
if (new_crtc_state->use_dsb)
intel_dsb_vblank_evade(state,
new_crtc_state->dsb_commit);
@@ -7375,6 +7372,16 @@ static void intel_atomic_dsb_finish(struct
intel_atomic_state *state,
intel_vrr_send_push(new_crtc_state->dsb_commit,
new_crtc_state);
+ /*
+ * Wait for idle is needed for corner case where
PSR HW
+ * is transitioning into DEEP_SLEEP/SRDENT_OFF
when
+ * new Frame Change event comes in. It is ok to do
it
+ * here for both Frame Change mecanisms (trans
s/mecanisms/mechanism
push
+ * and register write).
+ */
+ intel_psr_wait_for_idle_dsb(new_crtc_state-
dsb_commit,
+ new_crtc_state);
+
If I understand correctly:
For Fixed RR case:
Suppose we are in PSR:
Skip_wait_en is set.
The portion around the Send Push will be like:
-dsb_wait_vblank will no longer wait for the undelayed vblank (we are
in
PSR and skip_wait_en is set)
-we send push -> to trigger frame change event for PSR HW.
-After this PSR HW is supposed to receive the event and may be in
transition period so we wait for idle dsb.(which internally makes
sure
that we are out of PSR)
-We are not sure whether we are in active or in vblank region at this
point of time so we want to use dsb_wait_vblank. The skip_wait_en
will
now not come in picture since we have made sure that we are not in
PSR
in previous step.
Then other steps will be similar to what we have been doing.
Is my understanding correct?
What happens when Panel Replay is in picture, given we can have PR
enable with Variable Refresh Rate timings.
I don't know how having VRR enabled would impact this sequence? send
push triggers "Frame Change" event -> possible PR active is exited ->
wait for vblank -> wait_for_delayed_vblank -> check push is sent.
Do you have something specific in your mind?
Hmm yes you are right, as you have mentioned with skip_wait_en chicken
bit will make DSB jump the wait when Panel Replay is enabled.
Lets say we have VRR : ON and Panel Replay enabled.
-dsb_wait_vblank will no longer wait for the undelayed vblank (we are in PR and
skip_wait_en is set)
-we send push with send push bit and the frame change bit set.
This will now happen earlier than the case where Panel Replay was not in
picture, perhaps can be in active region.
This will also result in frame change event for PSR/PR HW.
-we then call intel_psr_wait_for_idle_dsb() that will make sure PR is out from
deep sleep state.
-We now wait for undelayed vblank which DSB will not jump because HW is not in
Panel Replay active mode.
-Then wait for delayed vblank, and check push sent etc should work as before.
Only thing to check now is DC balance thing done by DMC FW, but I guess since
HW is not in Panel Replay active state, it would not expect anything different
than the non Panel Replay situation.
In all, theoretically sequence looks alright to me.
There are a few nitpicks in commit message and comment.
Otherwise the patch LGTM.
Reviewed-by: Ankit Nautiyal <[email protected]>
BR,
Jouni Högander
Regards,
Ankit
/*
* In case PSR uses trans push as a "frame change"
event and
* VRR is not in use we need to wait vblank.
Othervise we may
