On Thu, Feb 7, 2019 at 10:20 AM Ard Biesheuvel <ard.biesheu...@linaro.org> wrote: > > On Wed, 6 Feb 2019 at 19:38, Christian König > <ckoenig.leichtzumer...@gmail.com> wrote: > > > > Am 06.02.19 um 18:23 schrieb Ard Biesheuvel: > > > On Fri, 25 Jan 2019 at 11:35, Ard Biesheuvel <ard.biesheu...@linaro.org> > > > wrote: > > >> On Fri, 25 Jan 2019 at 12:30, Christian König > > >> <ckoenig.leichtzumer...@gmail.com> wrote: > > >>> Am 25.01.19 um 09:43 schrieb Ard Biesheuvel: > > >>>> On Thu, 24 Jan 2019 at 15:01, Alex Deucher <alexdeuc...@gmail.com> > > >>>> wrote: > > >>>>> On Thu, Jan 24, 2019 at 9:00 AM Ard Biesheuvel > > >>>>> <ard.biesheu...@linaro.org> wrote: > > >>>>>> On Thu, 24 Jan 2019 at 13:31, Koenig, Christian > > >>>>>> <christian.koe...@amd.com> 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.koe...@amd.com> > > >>>>>>>> Cc: Alex Deucher <alexander.deuc...@amd.com> > > >>>>>>>> Cc: David Zhou <david1.z...@amd.com> > > >>>>>>>> Cc: Huang Rui <ray.hu...@amd.com> > > >>>>>>>> Cc: Junwei Zhang <jerry.zh...@amd.com> > > >>>>>>>> Cc: Michel Daenzer <michel.daen...@amd.com> > > >>>>>>>> Cc: David Airlie <airl...@linux.ie> > > >>>>>>>> Cc: Daniel Vetter <dan...@ffwll.ch> > > >>>>>>>> Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com> > > >>>>>>>> Cc: Maxime Ripard <maxime.rip...@bootlin.com> > > >>>>>>>> Cc: Sean Paul <s...@poorly.run> > > >>>>>>>> Cc: Michael Ellerman <m...@ellerman.id.au> > > >>>>>>>> Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org> > > >>>>>>>> Cc: Will Deacon <will.dea...@arm.com> > > >>>>>>>> Cc: Christoph Hellwig <h...@infradead.org> > > >>>>>>>> Cc: Robin Murphy <robin.mur...@arm.com> > > >>>>>>>> Cc: amd-gfx list <amd-gfx@lists.freedesktop.org> > > >>>>>>>> Cc: dri-devel <dri-de...@lists.freedesktop.org> > > >>>>>>>> Reported-by: Carsten Haitzler <carsten.haitz...@arm.com> > > >>>>>>>> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> > > >>>>>>> The subject line should probably read "disable uncached...". > > >>>>>>> > > >>>>>> Ugh, of course ... > > >>>>>> > > >>>>>>> With that fixed the patch is Reviewed-by: Christian König > > >>>>>>> <christian.koe...@amd.com>. > > >>>>>>> > > >>>>> Same: > > >>>>> Reviewed-by: Alex Deucher <alexander.deuc...@amd.com> > > >>>>> > > >>>> 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. Alex _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx
