On Thu, 7 Feb 2019 at 16:33, Alex Deucher <alexdeucher@xxxxxxxxx> wrote: > > On Thu, Feb 7, 2019 at 10:20 AM Ard Biesheuvel > <ard.biesheuvel@xxxxxxxxxx> wrote: > > > > On Wed, 6 Feb 2019 at 19:38, Christian König > > <ckoenig.leichtzumerken@xxxxxxxxx> wrote: > > > > > > Am 06.02.19 um 18:23 schrieb Ard Biesheuvel: > > > > On Fri, 25 Jan 2019 at 11:35, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote: > > > >> On Fri, 25 Jan 2019 at 12:30, Christian König > > > >> <ckoenig.leichtzumerken@xxxxxxxxx> wrote: > > > >>> Am 25.01.19 um 09:43 schrieb Ard Biesheuvel: > > > >>>> On Thu, 24 Jan 2019 at 15:01, Alex Deucher <alexdeucher@xxxxxxxxx> wrote: > > > >>>>> On Thu, Jan 24, 2019 at 9:00 AM Ard Biesheuvel > > > >>>>> <ard.biesheuvel@xxxxxxxxxx> wrote: > > > >>>>>> On Thu, 24 Jan 2019 at 13:31, Koenig, Christian > > > >>>>>> <Christian.Koenig@xxxxxxx> wrote: > > > >>>>>>> Am 24.01.19 um 13:06 schrieb Ard Biesheuvel: > > > >>>>>>>> The DRM driver stack is designed to work with cache coherent devices > > > >>>>>>>> only, but permits an optimization to be enabled in some cases, where > > > >>>>>>>> for some buffers, both the CPU and the GPU use uncached mappings, > > > >>>>>>>> removing the need for DMA snooping and allocation in the CPU caches. > > > >>>>>>>> > > > >>>>>>>> The use of uncached GPU mappings relies on the correct implementation > > > >>>>>>>> of the PCIe NoSnoop TLP attribute by the platform, otherwise the GPU > > > >>>>>>>> will use cached mappings nonetheless. On x86 platforms, this does not > > > >>>>>>>> seem to matter, as uncached CPU mappings will snoop the caches in any > > > >>>>>>>> case. However, on ARM and arm64, enabling this optimization on a > > > >>>>>>>> platform where NoSnoop is ignored results in loss of coherency, which > > > >>>>>>>> breaks correct operation of the device. Since we have no way of > > > >>>>>>>> detecting whether NoSnoop works or not, just disable this > > > >>>>>>>> optimization entirely for ARM and arm64. > > > >>>>>>>> > > > >>>>>>>> Cc: Christian Koenig <christian.koenig@xxxxxxx> > > > >>>>>>>> Cc: Alex Deucher <alexander.deucher@xxxxxxx> > > > >>>>>>>> Cc: David Zhou <David1.Zhou@xxxxxxx> > > > >>>>>>>> Cc: Huang Rui <ray.huang@xxxxxxx> > > > >>>>>>>> Cc: Junwei Zhang <Jerry.Zhang@xxxxxxx> > > > >>>>>>>> Cc: Michel Daenzer <michel.daenzer@xxxxxxx> > > > >>>>>>>> Cc: David Airlie <airlied@xxxxxxxx> > > > >>>>>>>> Cc: Daniel Vetter <daniel@xxxxxxxx> > > > >>>>>>>> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> > > > >>>>>>>> Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxx> > > > >>>>>>>> Cc: Sean Paul <sean@xxxxxxxxxx> > > > >>>>>>>> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > > > >>>>>>>> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > > > >>>>>>>> Cc: Will Deacon <will.deacon@xxxxxxx> > > > >>>>>>>> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> > > > >>>>>>>> Cc: Robin Murphy <robin.murphy@xxxxxxx> > > > >>>>>>>> Cc: amd-gfx list <amd-gfx@xxxxxxxxxxxxxxxxxxxxx> > > > >>>>>>>> Cc: dri-devel <dri-devel@xxxxxxxxxxxxxxxxxxxxx> > > > >>>>>>>> Reported-by: Carsten Haitzler <Carsten.Haitzler@xxxxxxx> > > > >>>>>>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > > > >>>>>>> The subject line should probably read "disable uncached...". > > > >>>>>>> > > > >>>>>> Ugh, of course ... > > > >>>>>> > > > >>>>>>> With that fixed the patch is Reviewed-by: Christian König > > > >>>>>>> <christian.koenig@xxxxxxx>. > > > >>>>>>> > > > >>>>> Same: > > > >>>>> Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx> > > > >>>>> > > > >>>> Thanks all > > > >>>> > > > >>>> Should I resend the patch with the subject corrected? > > > >>> I will update the subject line and push it upstream through > > > >>> drm-misc-next if nobody objects. > > > >>> > > > >> Wonderful, thanks. > > > > Hi Christian, > > > > > > > > Are you still planning to merge this for v5.1? > > > > > > My bad, only pushed this to our internal branch, but forgot out > > > drm-misc-next. > > > > > > Fixed now, thanks for the reminder. > > > > > > > Thanks, > > > > Does anyone mind if I propose this patch for backporting to v4.19 or > > earlier once it gets merged for v5.1? > > Go for it. I was going to suggest that this should probably go to stable. > Excellent. Note that I actually prefer sending it manually rather than let Greg or Sasha pick it up automatically, given that they are usually a bit trigger happy, i.e., patches tend to get backported before anyone has had a chance to actually check that it doesn't break anything in mainline. In other words, please don't add a cc -stable or fixes tag. I will track it myself instead. Thanks, Ard. _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
