On 07/02/2020 20:45, Ville Syrjälä wrote: > On Fri, Feb 07, 2020 at 08:26:17PM +0200, Jyri Sarha wrote: >> On 07/02/2020 20:18, Jyri Sarha wrote: >>> The old implementation of placing planes on the CRTC while configuring >>> the planes was naive and relied on the order in which the planes were >>> configured, enabled, and disabled. The situation where a plane's zpos >>> was changed on the fly was completely broken. The usual symptoms of >>> this problem was scrambled display and a flood of sync lost errors, >>> when a plane was active in two layers at the same time, or a missing >>> plane, in case when a layer was accidentally disabled. >>> >>> The rewrite takes a more straight forward approach when when HW is >>> concerned. The plane positioning registers are in the CRTC (or >>> actually OVR) register space and it is more natural to configure them >>> in a one go when configuring the CRTC. This is easy since we have >>> access to the whole atomic state when updating the CRTC configuration. >>> >> >> While implementing this fix it caught me by surprise that >> crtc->state->state (pointer up to full atomic state) is NULL when >> crtc_enable() or -flush() is called. So I take the plane-state directly >> from the plane->state and just assume that it is pointing to the same >> atomic state with the crtc state I am having. I that alraight? > > IMO you should never use plane->state etc. Better pass down the > full atomic state everywhere. Otherwise you can never even consider > increasing the commit queue depth since you'd end up accessing the > wrong state. > Ok. I did explore this a bit and it starts to look like that I have to store the planes' zpos values in the driver after all. Only the changes are available in the drm_atomic_state being commited so I have to maintain the full state myself. That is if I should not use plane->state in crtc_enable() or -flush(). >> >> Why is the crtc->state->state NULL? Is it a bug or is there some reason >> to it? > > Currently swap_state() moves that state pointer from the new obj state > to the old obj state, and clears the one in the new obj state. Not entirely > sure why, but maybe just so there isn't a stale ->state pointer hanging > around in the obj->state after the swap? > > I think a better way could be to not clobber the old obj state at > all, leave the new_obj_state->state alone, and just clear the ->state > pointer .duplicate_state(). But that would require reviewing a bunch > of code to find all the places where old_obj_state->state gets used > during the commit. > I think those places are many, since at least I did not figure out any other way to access the full commit behind the atomic helpers. -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
