On Thu, Feb 7, 2019 at 10:20 AM Ard Biesheuvel ard.biesheuvel@linaro.org wrote:
On Wed, 6 Feb 2019 at 19:38, Christian König ckoenig.leichtzumerken@gmail.com wrote:
Am 06.02.19 um 18:23 schrieb Ard Biesheuvel:
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?
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