On Fri, 25 Jan 2019 at 11:35, Ard Biesheuvel ard.biesheuvel@linaro.org wrote:
On Fri, 25 Jan 2019 at 12:30, Christian König ckoenig.leichtzumerken@gmail.com wrote:
Am 25.01.19 um 09:43 schrieb Ard Biesheuvel:
On Thu, 24 Jan 2019 at 15:01, Alex Deucher alexdeucher@gmail.com wrote:
On Thu, Jan 24, 2019 at 9:00 AM Ard Biesheuvel ard.biesheuvel@linaro.org wrote:
On Thu, 24 Jan 2019 at 13:31, Koenig, Christian Christian.Koenig@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.koenig@amd.com > Cc: Alex Deucher alexander.deucher@amd.com > Cc: David Zhou David1.Zhou@amd.com > Cc: Huang Rui ray.huang@amd.com > Cc: Junwei Zhang Jerry.Zhang@amd.com > Cc: Michel Daenzer michel.daenzer@amd.com > Cc: David Airlie airlied@linux.ie > Cc: Daniel Vetter daniel@ffwll.ch > Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com > Cc: Maxime Ripard maxime.ripard@bootlin.com > Cc: Sean Paul sean@poorly.run > Cc: Michael Ellerman mpe@ellerman.id.au > Cc: Benjamin Herrenschmidt benh@kernel.crashing.org > Cc: Will Deacon will.deacon@arm.com > Cc: Christoph Hellwig hch@infradead.org > Cc: Robin Murphy robin.murphy@arm.com > Cc: amd-gfx list amd-gfx@lists.freedesktop.org > Cc: dri-devel dri-devel@lists.freedesktop.org > Reported-by: Carsten Haitzler Carsten.Haitzler@arm.com > Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org The subject line should probably read "disable uncached...".
Ugh, of course ...
With that fixed the patch is Reviewed-by: Christian König christian.koenig@amd.com.
Same: Reviewed-by: Alex Deucher alexander.deucher@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?
Thanks, Ard.