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.
Christian.
Thanks,
Ard.
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