Den 06.11.2019 11.47, skrev Thomas Zimmermann:
> Simply removes all the obsolete GEM code from udl. No functional
> changes.
>
> Signed-off-by: Thomas Zimmermann <[email protected]>
> ---
> drivers/gpu/drm/udl/Makefile | 2 +-
> drivers/gpu/drm/udl/udl_dmabuf.c | 254 -------------------------------
> drivers/gpu/drm/udl/udl_drv.h | 29 ----
> drivers/gpu/drm/udl/udl_gem.c | 206 -------------------------
> 4 files changed, 1 insertion(+), 490 deletions(-)
> delete mode 100644 drivers/gpu/drm/udl/udl_dmabuf.c
>
<snip>
> -int udl_gem_vmap(struct udl_gem_object *obj)
> -{
> - int page_count = obj->base.size / PAGE_SIZE;
> - int ret;
> -
> - if (obj->base.import_attach) {
> - obj->vmapping = dma_buf_vmap(obj->base.import_attach->dmabuf);
> - if (!obj->vmapping)
> - return -ENOMEM;
> - return 0;
> - }
> -
> - ret = udl_gem_get_pages(obj);
> - if (ret)
> - return ret;
> -
> - obj->vmapping = vmap(obj->pages, page_count, 0, PAGE_KERNEL);
This differs from the shmem helper vmap:
shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
VM_MAP, pgprot_writecombine(PAGE_KERNEL));
Boris added the WC in be7d9f05c53e:
drm/gem_shmem: Use a writecombine mapping for ->vaddr
Right now, the BO is mapped as a cached region when ->vmap() is called
and the underlying object is not a dmabuf.
Doing that makes cache management a bit more complicated (you'd need
to call dma_map/unmap_sg() on the ->sgt field everytime the BO is about
to be passed to the GPU/CPU), so let's map the BO with writecombine
attributes instead (as done in most drivers).
I don't know what the implications of this are, just pointing out a
difference.
Noralf.
> - if (!obj->vmapping)
> - return -ENOMEM;
> - return 0;
> -}
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