On Thu, Apr 10, 2014 at 03:50:35PM -0700, Ben Widawsky wrote: > On Thu, Apr 10, 2014 at 06:51:50PM +0100, Damien Lespiau wrote: > > On Thu, Apr 10, 2014 at 10:32:46AM -0700, Ben Widawsky wrote: > > > On Thu, Apr 10, 2014 at 05:24:07PM +0100, Damien Lespiau wrote: > > > > While cruising through the specs, I noticed a note about swizzling changes on > > > > BDW. My understanding is that we don't need to either initialize swizzling on > > > > the GPU side nor swizzle the address ourselves on the CPU side. > > > > > > > > That could be totally wrong though, and I unfortunately don't have a machine to > > > > test this theory on. > > > > > > I fought with this too. My resolution was we can either set all the > > > swizzling bits, or set none. There is no motivation to do either, and > > > the spec simply is telling us what they do for windows. That was well > > > over a year ago, so it all can be different now. > > > > My (limited) understanding is telling me that if we don't return > > I915_BIT_6_SWIZZLE_NONE, user space is going to swizzle the address and > > the controller is going to swizzle it again, even from the CPU, so we > > end up at the wrong place. > > I thought this type of swizzling was usually determined by our code > i915_gem_detect_bit_6_swizzle(). I am also unfamiliar with whether or > not userspace controls it, and whether or not it should. I never really > looked at that aspect of the code. Maybe Chris can answer this part. Userspace only queries swizzling. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx