SHMEM-buffer backing storage is allocated from system memory; which is
typically cachable. The default mode for SHMEM objects is writecombine
though.
Unify SHMEM semantics by defaulting to cached mappings. The exception
is pages imported via dma-buf. DMA memory is usually not cached.
DRM drivers that require write-combined mappings set the map_wc flag
in struct drm_gem_shmem_object to true. This currently affects lima,
panfrost and v3d.
The drivers mgag200, udl, virtio and vkms continue to use default
shmem mappings.
The drivers cirrus and gm12u320 change caching flags. Both used
writecombine and now switch over to shmem defaults. Both drivers use
SHMEM objects as shadow buffers for internal video memory, so cached
mappings will not affect them negatively.
v3:
* set value of shmem pointer before dereferencing it in
__drm_gem_shmem_create() (Dan, kernel test robot)
v2:
* recreate patch on top of latest SHMEM helpers
* update lima, panfrost, v3d to select writecombine (Daniel, Rob)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201117133156.26822-2-tzimmermann@suse.de
This driver will be used to support Mesa on the Broadcom 7268 and 7278
platforms.
V3D 3.3 introduces an MMU, which means we no longer need CMA or vc4's
complicated CL/shader validation scheme. This massively changes the
GEM behavior, so I've forked off to a new driver.
v2: Mark SUBMIT_CL as needing DRM_AUTH. coccinelle fixes from kbuild
test robot. Drop personal git link from MAINTAINERS. Don't
double-map dma-buf imported BOs. Add kerneldoc about needing MMU
eviction. Drop prime vmap/unmap stubs. Delay mmap offset setup
to mmap time. Use drm_dev_init instead of _alloc. Use
ktime_get() for wait_bo timeouts. Drop drm_can_sleep() usage,
since we don't modeset. Switch page tables back to WC (debug
change to coherent had slipped in). Switch
drm_gem_object_unreference_unlocked() to
drm_gem_object_put_unlocked(). Simplify overflow mem handling by
not sharing overflow mem between jobs.
v3: no changes
v4: align submit_cl to 64 bits (review by airlied), check zero flags in
other ioctls.
Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> (v4)
Acked-by: Dave Airlie <airlied@linux.ie> (v3, requested submit_cl change)
Link: https://patchwork.freedesktop.org/patch/msgid/20180430181058.30181-3-eric@anholt.net
