On Tue, 27 Nov 2012 08:22:01 +0000 Chris Wilson <chris at chris-wilson.co.uk> wrote: > On Mon, 26 Nov 2012 21:52:54 -0800, Ben Widawsky <ben at bwidawsk.net> > wrote: > > This bug was introduced by me: > > commit e76e9aebcdbfebae8f4cd147e3c0f800d36e97f3 > > Author: Ben Widawsky <ben at bwidawsk.net> > > Date: Sun Nov 4 09:21:27 2012 -0800 > > > > drm/i915: Stop using AGP layer for GEN6+ > > > > The existing code uses memset_io which follows memset semantics in > > only guaranteeing a write of individual bytes. Since a PTE entry is > > 4 bytes, this can only be correct if the scratch page address is 0. > > Gah. Wasn't there an iowrite32_rep? And you would hope it does what you want... but it seems like just a memcpy of dword sized chunks. My first thought was to write my own memset which does what you want, but this seemed like a path of less resistance. > > > This caused unsightly errors when we clear the range at load time, > > though I'm not really sure what the heck is referencing that memory > > anyway. I caught this is because I believe we have some other bug > > where the display is doing reads of memory we feel should be > > cleared (or we are relying on scratch pages to be a specific value). > > That's just because we are no longer disabling outputs before updating > the GTT and hence continue to scanout from the BIOS fb during module > load. It's a regression that we'll be able to finally fix properly > with fastboot - though that will not be without its downsides either. > -Chris >
