Quoting Animesh Manna (2019-10-21 11:11:04) > > > On 10/17/2019 8:08 PM, Tvrtko Ursulin wrote: > > > > On 17/10/2019 14:53, Animesh Manna wrote: > >> On 10/17/2019 6:39 PM, Tvrtko Ursulin wrote: > >>> On 17/10/2019 13:52, Animesh Manna wrote: > >>>> On 10/17/2019 2:05 PM, Tvrtko Ursulin wrote: > >>>>> On 22/08/2019 13:09, Chris Wilson wrote: > >>>>>> Quoting Animesh Manna (2019-08-22 13:05:06) > >>>>>>> Hi, > >>>>>>> > >>>>>>> > >>>>>>> On 8/21/2019 11:41 PM, Chris Wilson wrote: > >>>>>>>> Quoting Animesh Manna (2019-08-21 07:32:22) > >>>>>>>>> + vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, > >>>>>>>>> PIN_MAPPABLE); > >>>>>>>> Only this (currently) still requires struct_mutex > >>>>>>> > >>>>>>> Sure will add. > >>>>>>>> > >>>>>>>> Does it have to mappable? Is that the HW constraint? > >>>>>>> > >>>>>>> Yes, as per HW design need a cpu mapped buffer to write > >>>>>>> opcode+data from > >>>>>>> driver. > >>>>>> > >>>>>> PIN_MAPPABLE refers to the iomem aperture portion of the Global > >>>>>> GTT (i.e. > >>>>>> the low 64-512MiB). You never use a GGTT mmap for your CPU > >>>>>> access, so the > >>>>>> placement should be entirely dictated by the DSB requirements. If > >>>>>> you > >>>>>> don't need to be in the low region, don't force it to be, so we have > >>>>>> less congestion for the objects that have to be placed in that > >>>>>> region. > >>>>> > >>>>> I was doing a mini audit of what uses the aperture these days and > >>>>> noticed this code has been merged in the meantime, but AFAICS this > >>>>> question from Chris hasn't been answered? At least not on the > >>>>> mailing list. So does it need to be in the aperture region or not? > >>>> > >>>> Hi, > >>>> > >>>> Based on recommendation from H/w team used PIN_MAPPABLE, not very > >>>> sure about internal details. > >>> > >>> What did the recommendation exactly say? That it has to be in GGTT > >>> or aperture? > >> > >> It said: > >> "GMM to allocate buffer from global GTT, get CPU mapped address as > >> well (not stolen memory) ... ". > > > > So it's possible you don't need PIN_MAPPABLE. > > As per I remember from initial discussion from h/w team DSB is not cache > coherent. Due to that we have used I915_MAP_WC during mapping the buffer > and want to keep the buffer in aperture region. The mappable aperture has nothing to do with I915_MAP_WC which is a processor attribute on its page tables. If only I mentioned we had a way to flush caches! -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
