On Thu, 7 Feb 2019 at 16:33, Alex Deucher alexdeucher@gmail.com wrote:
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.
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.