mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-08-27 03:10:12 +00:00
Code Issues Releases Wiki Activity

drm/cma-helper: Set VM_DONTEXPAND for mmap

Browse source 
drm_gem_cma_mmap() cannot assume every implementation of dma_mmap_wc()
will end up calling remap_pfn_range() (which happens to set the relevant
vma flag, among others), so in order to make sure expectations around
VM_DONTEXPAND are met, let it explicitly set the flag like most other
GEM mmap implementations do.

This avoids repeated warnings on a small minority of systems where the
display is behind an IOMMU, and has a simple driver which does not
override drm_gem_cma_default_funcs. Arm hdlcd is an in-tree affected
driver. Out-of-tree, the Apple DCP driver is affected; this fix is
required for DCP to be mainlined.

[Alyssa: Update commit message.]

Fixes: c40069cb7b ("drm: add mmap() to drm_gem_object_funcs")
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211013143654.39031-1-alyssa@rosenzweig.io
This commit is contained in:
Robin Murphy 2021-10-13 10:36:54 -04:00 committed by Alyssa Rosenzweig
parent 9da1e9ab82
commit 59f39bfa65
1 changed files with 1 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
drivers/gpu/drm/drm_gem_cma_helper.c
View file

@ -512,6 +512,7 @@ int drm_gem_cma_mmap(struct drm_gem_cma_object *cma_obj, struct vm_area_struct *
*/
vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
vma->vm_flags &= ~VM_PFNMAP;
vma->vm_flags |= VM_DONTEXPAND;
if (cma_obj->map_noncoherent) {
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);