> -----Original Message----- > From: Chris Wilson [mailto:chris@xxxxxxxxxxxxxxxxxx] > Sent: Tuesday, May 23, 2017 1:41 AM > To: Bloomfield, Jon <jon.bloomfield@xxxxxxxxx> > Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH] drm/i915: Serialize GTT Updates on BXT > > On Mon, May 22, 2017 at 11:07:25AM -0700, Jon Bloomfield wrote: > > BXT requires accesses to the GTT (i.e. PTE updates) to be serialized > > when IOMMU is enabled. This patch guarantees this by wrapping all > > updates in stop_machine and using a flushing read to guarantee that > > the GTT writes have reached their destination before restarting. > > > > Testcase? igt/gem_concurrent_blit shows the failure. I was using a combination of tests, run in parallel to hit this bug. I need to get hold of a system again to re-run. Are you saying you have also repro'd the bug just with gem_concurrent_blit or just suggesting that it might be a good candidate ? I'll also re-try without the flushing read, but I'm wary of removing this unless I can understand why the mmio write has the same effect. It might be luck. > -Chris > > -- > Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
