On Fri, Jan 27, 2017 at 09:30:50AM +0000, Chris Wilson wrote: > On Thu, Jan 26, 2017 at 04:59:21PM +0100, Maarten Lankhorst wrote: > > When writing some testcases for nonblocking modesets. I found out that the > > infinite wait on the old fb was causing issues. > > The crux of the issue here is the locked wait for old dependencies and > the inability to inject the intel_prepare_reset disabling of all planes. > There are a couple of locked waits on struct_mutex within the modeset > locks for intel_overlay and if we happen to be using the display plane > for the first time. > > The first I suggested solving using fences to track dependencies and > keep the order between atomic states. Cancelling the outstanding > modesets, replacing with a disable and then on restore jumping to the > final state look doable. It also requires avoiding the struct_mutex for > disabling, which is quite easy. To avoid the wait under struct_mutex, > we've talked about switching to mmio, but for starters we could move the > wait from inside intel_overlay into the fence for the atomic operation. > (But's that a little more surgery than we would like for intel_overlay I > guess - dig out Ville's patches for overlay planes?) And to prevent the > wait under struct_mutex for pin_to_display_plane, my plane is to move > that to an async fenced operation that is then naturally waited upon by > the atomic modeset. A bit more a hack, but a different idea, and I think hack for gen234.0 is ok: We complete all the requests before we start the hw reset with fence.error = -EIO. But we do this only when we need to get at the display locks. A slightly more elegant solution would be to trylock modeset locks, and if one of them fails (and only then) complete all requests with -EIO to get the concurrent modeset to proceed before we reset the hardware. That's essentially the logic we had before all the reworks, and it worked. But I didn't look at how scary that all would be to make it work again ... -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
