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 --- include/drm/drm_cache.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
diff --git a/include/drm/drm_cache.h b/include/drm/drm_cache.h index bfe1639df02d..97fc498dc767 100644 --- a/include/drm/drm_cache.h +++ b/include/drm/drm_cache.h @@ -47,6 +47,24 @@ static inline bool drm_arch_can_wc_memory(void) return false; #elif defined(CONFIG_MIPS) && defined(CONFIG_CPU_LOONGSON3) return false; +#elif defined(CONFIG_ARM) || defined(CONFIG_ARM64) + /* + * 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. + */ + return false; #else return true; #endif
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...".
With that fixed the patch is Reviewed-by: Christian König christian.koenig@amd.com.
Regards, Christian.
include/drm/drm_cache.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
diff --git a/include/drm/drm_cache.h b/include/drm/drm_cache.h index bfe1639df02d..97fc498dc767 100644 --- a/include/drm/drm_cache.h +++ b/include/drm/drm_cache.h @@ -47,6 +47,24 @@ static inline bool drm_arch_can_wc_memory(void) return false; #elif defined(CONFIG_MIPS) && defined(CONFIG_CPU_LOONGSON3) return false; +#elif defined(CONFIG_ARM) || defined(CONFIG_ARM64)
- /*
* 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.*/- return false; #else return true; #endif
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.
Thanks.
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. _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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?
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.
Christian.
dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
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.
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.
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.
Christian.
Thanks, Ard. _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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?
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
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.
dri-devel@lists.freedesktop.org
-
Alex Deucher -
Ard Biesheuvel -
Christian König -
Koenig, Christian