On 28/05/2021 02:03, Paul Cercueil wrote:
The previous commit wrongly assumed that dma_mmap_wc() could be replaced
by pgprot_writecombine() + dma_mmap_pages(). It did work on my setup,
but did not work everywhere.
Use dma_mmap_wc() when the buffer has the write-combine cache attribute,
and dma_mmap_pages() when it has the non-coherent cache attribute.
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
Reported-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Fixes: cf8ccbc72d61 ("drm: Add support for GEM buffers backed by non-coherent memory")
---
drivers/gpu/drm/drm_gem_cma_helper.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 235c7a63da2b..4c3772651954 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -514,13 +514,17 @@ int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
cma_obj = to_drm_gem_cma_obj(obj);
- vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
- if (!cma_obj->map_noncoherent)
- vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
+ if (cma_obj->map_noncoherent) {
+ vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+
+ ret = dma_mmap_pages(cma_obj->base.dev->dev,
+ vma, vma->vm_end - vma->vm_start,
+ virt_to_page(cma_obj->vaddr));
+ } else {
+ ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
+ cma_obj->paddr, vma->vm_end - vma->vm_start);
- ret = dma_mmap_pages(cma_obj->base.dev->dev,
- vma, vma->vm_end - vma->vm_start,
- virt_to_page(cma_obj->vaddr));
+ }
if (ret)
drm_gem_vm_close(vma);
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
and
Tested-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Thanks!
Btw, the kernel-doc for drm_gem_cma_create doesn't quite match, as it
says wc is always used.
Tomi
