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Subject[PATCH v4 1/3] drm/shmem: add support for per object caching flags.
Date
Add map_cached bool to drm_gem_shmem_object, to request cached mappings
on a per-object base. Check the flag before adding writecombine to
pgprot bits.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
include/drm/drm_gem_shmem_helper.h | 5 +++++
drivers/gpu/drm/drm_gem_shmem_helper.c | 12 +++++++++---
2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 6748379a0b44..e69f58d467c6 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -83,6 +83,11 @@ struct drm_gem_shmem_object {
* The address are un-mapped when the count reaches zero.
*/
unsigned int vmap_use_count;
+
+ /**
+ * @map_cached: map object cached (instead of using writecombine).
+ */
+ bool map_cached;
};

#define to_drm_gem_shmem_obj(obj) \
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index a421a2eed48a..443265a4fc5a 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -256,9 +256,13 @@ static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)

if (obj->import_attach)
shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
- else
+ else {
+ pgprot_t prot = PAGE_KERNEL;
+ if (!shmem->map_cached)
+ prot = pgprot_writecombine(prot);
shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
- VM_MAP, pgprot_writecombine(PAGE_KERNEL));
+ VM_MAP, prot);
+ }

if (!shmem->vaddr) {
DRM_DEBUG_KMS("Failed to vmap pages\n");
@@ -540,7 +544,9 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
}

vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
- vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+ vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+ if (!shmem->map_cached)
+ vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
vma->vm_ops = &drm_gem_shmem_vm_ops;

--
2.18.1
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