Re: [PATCH] drm/i915: do not reset PLANE_SURF on plane disable on older gens

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 06.09.2022 13:22, Ville Syrjälä wrote:
On Tue, Sep 06, 2022 at 01:09:16PM +0200, Andrzej Hajda wrote:

On 05.09.2022 19:44, Ville Syrjälä wrote:
On Mon, Sep 05, 2022 at 07:02:40PM +0200, Andrzej Hajda wrote:
On 05.09.2022 13:48, Ville Syrjälä wrote:
On Mon, Sep 05, 2022 at 10:05:00AM +0200, Andrzej Hajda wrote:
In case of ICL and older generations disabling plane and/or disabling
async update is always performed on vblank,
It should only be broken on bdw-glk (see. need_async_flip_disable_wa).
On CFL it is reported every drmtip run:
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip.html?testfilter=tiled-max-hw
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_1209/fi-cfl-8109u/igt@kms_big_fb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx#dmesg-warnings402
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_1209/fi-cfl-8109u/igt@kms_big_fb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx#dmesg-warnings402
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_1209/fi-cfl-8109u/igt@kms_big_fb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_1208/fi-cfl-8109u/igt@kms_big_fb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
...
On APL it is less frequent, probably due to other bugs preventing run of
this test, last seen at:
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_1190/fi-apl-guc/igt@kms_big_fb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Similar for SKL:
https://intel-gfx-ci.01.org/tree/drm-tip/drmtip_1181/fi-skl-guc/igt@kms_big_fb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

I am not sure if I correctly read the docs but [1] says that 9th bit of
PLANE_CFG (Async Address Update Enable) is "not double buffered and the
changes will apply immediately" only for ICL, JSL, LKF1.
It got broken in bdw and fixed again in icl.

So the change is not necessary in case of icl_plane_disable_arm.

[1]: https://gfxspecs.intel.com/Predator/Home/Index/7656
but if async update is enabled
PLANE_SURF register is updated asynchronously. Writing 0 to PLANE_SURF
when plane is still enabled can cause DMAR/PIPE errors.
On the other side PLANE_SURF is used to arm plane registers - we need to
write to it to trigger update on VBLANK, writting current value should
be safe - the buffer address is valid till vblank.
I think you're effectively saying that somehow the async
flip disable w/a is not kicking in sometimes.
I was not aware of existence of this w/a and I am little lost in
figuring out how this w/a can prevent zeroing PLANE_SURF too early.
When it works as designed it should:
1. turn off the async flip bit
2. wait for vblank so that gets latched
3. do the sync plane update/disable normally
After debugging this terra incognita, I've figured out that plane states
are not populated in intel_crtc_async_flip_disable_wa
so for_each_old_intel_plane_in_state does not iterate over affected
planes and w/a does not work at all.
I have no idea where affected plane states should be added.
Adding them to the beginning of intel_atomic_check helped, but this is
just blind shot:

@@ -6778,10 +6778,14 @@ static int intel_atomic_check(struct drm_device
*dev,
               new_crtc_state->uapi.mode_changed = true;

           if (new_crtc_state->uapi.scaling_filter !=
               old_crtc_state->uapi.scaling_filter)
               new_crtc_state->uapi.mode_changed = true;
+
+        ret = intel_atomic_add_affected_planes(state, crtc);
+        if (ret)
+            goto fail;
       }

       intel_vrr_check_modeset(state);

       ret = drm_atomic_helper_check_modeset(dev, &state->base);
               ^
This guy should be adding them for any crtc that has been flagged
for modeset ahead of time. For modesets flagged later we have to
add them by hand (eg. in intel_modeset_all_pipes()).

This is no-modeset scenario, drm_atomic_helper_check_modeset does not add planes in this case.

Btw, tested your warns from another mail, none appeared.

Regards
Andrzej


For normal plane updates the relevant planes are already added
when the property values are updated.


Let me know if there is better place/way to handle it.

Regards
Andrzej




[Index of Archives]     [AMD Graphics]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux