On Tue, Sep 06, 2022 at 05:14:56PM +0300, Ville Syrjälä wrote: > On Tue, Sep 06, 2022 at 03:57:37PM +0200, Andrzej Hajda wrote: > > > > > > 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. > > Then he mystery is how intel_crtc_async_flip_disable_wa() manages > to not disable async flip for some planes... After a few minutes of pondering I have a theory: 1. async flip on plane 1 crtc_state.*async_flip: false -> true 2. sync flip on plane 2, plane 1 not include in state crtc_state.*async_flip: true -> false, but plane 1 still remains in async flip mode 3. sync update/disable plane 1 crtc_state.*async_flip = true -> true, so the async flip disable w/a is not triggeed Should be easy to type up a dedicated test case for that. I think there are two options of handling this: - Switch all planes out of async flip mode for any sync update. Not great because then you can't mix async flips with any other sync updates on the same crtc - Start tracking which planes are in async flip mode vs. not Should allow more freedom in mixing async flips with other updates on the crtc -- Ville Syrjälä Intel
