On Thu, Apr 6, 2017 at 4:10 PM, Thomas Hellstrom <thellstrom@xxxxxxxxxx> wrote: > On 04/06/2017 02:34 PM, Daniel Vetter wrote: >> Hi Thomas, >> >> Bisected an offender already? Afaik there's no one else who reported >> issues thus far, and for our own CI it seems all still fine. >> -Daniel > > Hi, Daniel, > > Yes, I rebased drm-misc-next on top of vmwgfx-next and found the culprit > to be > > 38b6441e "drm/atomic-helper: Remove the backoff hack from set_config.." > > Reverting first 1fa4da04 and then > 38b6441e > > fixes the problem. Yeah, we seem to have a solid functional conflict between the vmwgfx atomic conversion, and the changes in drm-misc-next. Preliminary analysis, but I think what's going on is: - With the above changes in -misc we punt the deadlock retry loop to the callers of ->set_config. - But since it would have been way too invasive, I only fixed up the atomic callers (in most places we have special paths for atomic and non-atomic due to slightly different semantics), which means for legacy functions we in some cases pass a NULL ctx down to ->set_config. But since legacy paths only get called on legacy drivers, no problem. - Well except I've done that audit before vmwgfx became atomic, and that audit is now wrong, and I've forgotten to properly re-audit when the conflicts happened all around. But since I half-expect to hit a mid-driver conversion with this I did sprinkle WARN_ON(drm_drv_uses_atomic_modeset()) over all these paths. So assuming this is correct, you should see a pile of WARN_ON backtraces that you're hitting in the atomic-vmwgfx+drm-misc-next combo. The proper fix would be to switch over to atomic primitives for all these cases. On a quick look I see some in the vmwgfx fbdev emulation code, might even be worth it to check whether we could reuse the core helpers (which do this split handling alread) in some cases. Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
