Module Name: src
Committed By: jmcneill
Date: Sun Jan 19 12:03:27 UTC 2020
Modified Files:
src/sys/external/bsd/drm2/dist/include/drm: drm_cache.h
src/sys/external/bsd/drm2/include/drm: drm_os_netbsd.h
Log Message:
Disable the use of WC memory on Arm and Arm64. From Linux:
* 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.
To generate a diff of this commit:
cvs rdiff -u -r1.2 -r1.3 \
src/sys/external/bsd/drm2/dist/include/drm/drm_cache.h
cvs rdiff -u -r1.15 -r1.16 \
src/sys/external/bsd/drm2/include/drm/drm_os_netbsd.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
