Hi, On Wed, Jan 31, 2024 at 05:27:14AM +0000, Jason-JH Lin (林睿祥) wrote: > > On Sun, 2024-01-28 at 10:24 +0100, Maxime Ripard wrote: > > On Thu, Jan 25, 2024 at 07:17:21PM +0100, Daniel Vetter wrote: > > > On Tue, Jan 23, 2024 at 06:09:05AM +0000, Jason-JH Lin (林睿祥) wrote: > > > > Hi Maxime, Daniel, > > > > > > > > We encountered similar issue with mediatek SoCs. > > > > > > > > We have found that in drm_atomic_helper_commit_rpm(), when > > > > disabling > > > > the cursor plane, the old_state->legacy_cursor_update in > > > > drm_atomic_wait_for_vblank() is set to true. > > > > As the result, we are not actually waiting for a vlbank to wait > > > > for our > > > > hardware to close the cursor plane. Subsequently, the execution > > > > proceeds to drm_atomic_helper_cleanup_planes() to free the > > > > cursor > > > > buffer. This can lead to use-after-free issues with our hardware. > > > > > > > > Could you please apply this patch to fix our problem? > > > > Or are there any considerations for not applying this patch? > > > > > > Mostly it needs someone to collect a pile of acks/tested-by and > > > then land > > > it. > > > > > > I'd be _very_ happy if someone else can take care of that ... > > > > > > There's also the potential issue that it might slow down some of > > > the > > > legacy X11 use-cases that really needed a non-blocking cursor, but > > > I think > > > all the drivers where this matters have switched over to the async > > > plane > > > update stuff meanwhile. So hopefully that's good. > > > > I think there was also a regression with msm no one really figured > > out? > > OK... > But I am only available on MediaTek platform. I think most of us are in that situation, and which is part of the reason it kind of stalled :) > Does it also causes a regression with msn if I re-send a patch for > drm_atomic_helper.c only? Yes, that's my recollection at least. Fortunately, Dmitry might be able to clear that up. Maxime
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