diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index b46bdb8985da..bbfefb29c211 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -300,16 +300,7 @@ static void mtk_drm_kms_deinit(struct drm_device *drm)
 	component_unbind_all(drm->dev, drm);
 }
 
-static const struct file_operations mtk_drm_fops = {
-	.owner = THIS_MODULE,
-	.open = drm_open,
-	.release = drm_release,
-	.unlocked_ioctl = drm_ioctl,
-	.mmap = mtk_drm_gem_mmap,
-	.poll = drm_poll,
-	.read = drm_read,
-	.compat_ioctl = drm_compat_ioctl,
-};
+DEFINE_DRM_GEM_FOPS(mtk_drm_fops);
 
 /*
  * We need to override this because the device used to import the memory is
@@ -332,7 +323,7 @@ static const struct drm_driver mtk_drm_driver = {
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_import = mtk_drm_gem_prime_import,
 	.gem_prime_import_sg_table = mtk_gem_prime_import_sg_table,
-	.gem_prime_mmap = mtk_drm_gem_mmap_buf,
+	.gem_prime_mmap = drm_gem_prime_mmap,
 	.fops = &mtk_drm_fops,
 
 	.name = DRIVER_NAME,
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
index 280ea0d5e840..d0544962cfc1 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
@@ -14,11 +14,14 @@
 #include "mtk_drm_drv.h"
 #include "mtk_drm_gem.h"
 
+static int mtk_drm_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
+
 static const struct drm_gem_object_funcs mtk_drm_gem_object_funcs = {
 	.free = mtk_drm_gem_free_object,
 	.get_sg_table = mtk_gem_prime_get_sg_table,
 	.vmap = mtk_drm_gem_prime_vmap,
 	.vunmap = mtk_drm_gem_prime_vunmap,
+	.mmap = mtk_drm_gem_object_mmap,
 	.vm_ops = &drm_gem_cma_vm_ops,
 };
 
@@ -145,11 +148,19 @@ static int mtk_drm_gem_object_mmap(struct drm_gem_object *obj,
 	struct mtk_drm_gem_obj *mtk_gem = to_mtk_gem_obj(obj);
 	struct mtk_drm_private *priv = obj->dev->dev_private;
 
+	/*
+	 * Set vm_pgoff (used as a fake buffer offset by DRM) to 0 and map the
+	 * whole buffer from the start.
+	 */
+	vma->vm_pgoff = 0;
+
 	/*
 	 * dma_alloc_attrs() allocated a struct page table for mtk_gem, so clear
 	 * VM_PFNMAP flag that was set by drm_gem_mmap_obj()/drm_gem_mmap().
 	 */
-	vma->vm_flags &= ~VM_PFNMAP;
+	vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+	vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
 
 	ret = dma_mmap_attrs(priv->dma_dev, vma, mtk_gem->cookie,
 			     mtk_gem->dma_addr, obj->size, mtk_gem->dma_attrs);
@@ -159,37 +170,6 @@ static int mtk_drm_gem_object_mmap(struct drm_gem_object *obj,
 	return ret;
 }
 
-int mtk_drm_gem_mmap_buf(struct drm_gem_object *obj, struct vm_area_struct *vma)
-{
-	int ret;
-
-	ret = drm_gem_mmap_obj(obj, obj->size, vma);
-	if (ret)
-		return ret;
-
-	return mtk_drm_gem_object_mmap(obj, vma);
-}
-
-int mtk_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
-{
-	struct drm_gem_object *obj;
-	int ret;
-
-	ret = drm_gem_mmap(filp, vma);
-	if (ret)
-		return ret;
-
-	obj = vma->vm_private_data;
-
-	/*
-	 * Set vm_pgoff (used as a fake buffer offset by DRM) to 0 and map the
-	 * whole buffer from the start.
-	 */
-	vma->vm_pgoff = 0;
-
-	return mtk_drm_gem_object_mmap(obj, vma);
-}
-
 /*
  * Allocate a sg_table for this GEM object.
  * Note: Both the table's contents, and the sg_table itself must be freed by
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.h b/drivers/gpu/drm/mediatek/mtk_drm_gem.h
index 6da5ccb4b933..9a359a06cb73 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.h
@@ -39,9 +39,6 @@ struct mtk_drm_gem_obj *mtk_drm_gem_create(struct drm_device *dev, size_t size,
 					   bool alloc_kmap);
 int mtk_drm_gem_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
 			    struct drm_mode_create_dumb *args);
-int mtk_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
-int mtk_drm_gem_mmap_buf(struct drm_gem_object *obj,
-			 struct vm_area_struct *vma);
 struct sg_table *mtk_gem_prime_get_sg_table(struct drm_gem_object *obj);
 struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
 			struct dma_buf_attachment *attach, struct sg_table *sg);
