drm/msm: use the right pgprot when mapping BOs in the kernel

Use the same logic as the userspace mapping.

This fixes msm_rd with cached BOs.
Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Acked-by: Jordan Crouse <jordan@cosmicpenguin.net>
Link: https://lore.kernel.org/r/20210423190833.25319-4-jonathan@marek.caSigned-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_gem.c

@@ -211,6 +211,15 @@ void msm_gem_put_pages(struct drm_gem_object *obj)
 	msm_gem_unlock(obj);
 }
 
+static pgprot_t msm_gem_pgprot(struct msm_gem_object *msm_obj, pgprot_t prot)
+{
+	if (msm_obj->flags & MSM_BO_WC)
+		return pgprot_writecombine(prot);
+	if (msm_obj->flags & MSM_BO_UNCACHED)
+		return pgprot_noncached(prot);
+	return prot;
+}
+
 int msm_gem_mmap_obj(struct drm_gem_object *obj,
 		struct vm_area_struct *vma)
 {
@@ -218,13 +227,7 @@ int msm_gem_mmap_obj(struct drm_gem_object *obj,
 
 	vma->vm_flags &= ~VM_PFNMAP;
 	vma->vm_flags |= VM_MIXEDMAP;
-
-	if (msm_obj->flags & MSM_BO_WC)
-		vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
-	else if (msm_obj->flags & MSM_BO_UNCACHED)
-		vma->vm_page_prot = pgprot_noncached(vm_get_page_prot(vma->vm_flags));
-	else
-		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+	vma->vm_page_prot = msm_gem_pgprot(msm_obj, vm_get_page_prot(vma->vm_flags));
 
 	return 0;
 }
@@ -644,7 +647,7 @@ static void *get_vaddr(struct drm_gem_object *obj, unsigned madv)
 			goto fail;
 		}
 		msm_obj->vaddr = vmap(pages, obj->size >> PAGE_SHIFT,
-				VM_MAP, pgprot_writecombine(PAGE_KERNEL));
+				VM_MAP, msm_gem_pgprot(msm_obj, PAGE_KERNEL));
 		if (msm_obj->vaddr == NULL) {
 			ret = -ENOMEM;
 			goto fail;