Hi Piotr, On Tue Jun 10, 2025 at 12:37 AM CEST, Piotr Zalewski wrote: > Hi Diederik, sorry for late response
No need to be sorry :-) (late? Less then 2 days vs my ~4 months before the git bisect ...) >> Interesting that it also happened with drm=y. > > I actually checked now and i don't have the issue with drm=y, sorry for > misinforming you all, hopefully no one's time was wasted. Good to know, thanks :-) >> > happened twice and at short interval and since this patch allows for gamma >> > LUT update regardless of color_mgmt_changed state this makes DSP CTRL GAMMA >> > LUT EN bit to be unset twice too. It seems that VOP does not like it. I >> >> Happy to see you found the cause :-) >> Do you happen to know why it was unset twice? That sounds suboptimal. > > It is due to DRM modeset which can happens when CRTC (display) config changes > "significantly". AFAIK modeset happens def. when you go out of suspend or > display timings change. I might have been fooled by serial console last time > as it does not appear to happen twice in short interval when i review the > journal entries. > >> But (IIUC) setting a bit to a value it already has causing issues, >> sounds surprising as well. > > Depends on what hardware does, when you write to a register it might cause > many other things to happen and seems like for vop2 it messes something up. I didn't know that, thanks. > I made a second patch so that the first write is not permitted but all > subsequent are permitted (regardless of lut en state) - issue disappeared > too. So it might be that very first write to dsp lut disable happens too > fast (in relation to something else)?. It is not intuitive because when drm is > a module it happens usually like ~second later. > > part of the log with drm=y > ``` > [ 6.543099] rockchip-drm display-subsystem: [drm] GAMMA LUT DISABLE > ``` > > part of the log with drm=m > ``` > [ 7.944120] rockchip-drm display-subsystem: [drm] GAMMA LUT DISABLE > ``` My first (uneducated) hunch was a timing issue and ``=m`` can reveal issues which you wouldn't see with ``=y``. Andy already found an issue "that shouldn't happen" and my latest test also had an unexpected result. So (eventually) we'll figure it out :-) >> Sounds like a plan. It could be that this issue surfaced an underlaying >> issue and if so, fixing that would be even better. > > When i have time this week I will check on what version of the kernel i > tested gamma lut when i sent the patches and test there. I think it would be beneficial if you'd do the tests that Andy asked 'me' to do too, so we can compare results. FWIW: I have the 4GB RAM version. Cheers, Diederik
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