drm/etnaviv: call correct function when trying to vmap a DMABUF

When trying to get the vmap address of an imported buffer, we must
call into the appropriate helper function, to allow the exporter to
establish the vmap, instead of trying to vmap the buffer on our own.

Add an indirection through etnaviv_gem_ops to allow the correct
implementation to be called.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -357,21 +357,33 @@ void *etnaviv_gem_vmap(struct drm_gem_object *obj)
 {
 	struct etnaviv_gem_object *etnaviv_obj = to_etnaviv_bo(obj);
 
-	mutex_lock(&etnaviv_obj->lock);
-	if (!etnaviv_obj->vaddr) {
-		struct page **pages = etnaviv_gem_get_pages(etnaviv_obj);
+	if (etnaviv_obj->vaddr)
+		return etnaviv_obj->vaddr;
 
-		if (IS_ERR(pages)) {
+	mutex_lock(&etnaviv_obj->lock);
+	/*
+	 * Need to check again, as we might have raced with another thread
+	 * while waiting for the mutex.
+	 */
+	if (!etnaviv_obj->vaddr)
+		etnaviv_obj->vaddr = etnaviv_obj->ops->vmap(etnaviv_obj);
 	mutex_unlock(&etnaviv_obj->lock);
+
+	return etnaviv_obj->vaddr;
+}
+
+static void *etnaviv_gem_vmap_impl(struct etnaviv_gem_object *obj)
+{
+	struct page **pages;
+
+	lockdep_assert_held(&obj->lock);
+
+	pages = etnaviv_gem_get_pages(obj);
+	if (IS_ERR(pages))
 		return NULL;
-		}
 
-		etnaviv_obj->vaddr = vmap(pages, obj->size >> PAGE_SHIFT,
+	return vmap(pages, obj->base.size >> PAGE_SHIFT,
 			VM_MAP, pgprot_writecombine(PAGE_KERNEL));
-	}
-	mutex_unlock(&etnaviv_obj->lock);
-
-	return etnaviv_obj->vaddr;
 }
 
 static inline enum dma_data_direction etnaviv_op_to_dma_dir(u32 op)
@@ -524,6 +536,7 @@ static void etnaviv_gem_shmem_release(struct etnaviv_gem_object *etnaviv_obj)
 static const struct etnaviv_gem_ops etnaviv_gem_shmem_ops = {
 	.get_pages = etnaviv_gem_shmem_get_pages,
 	.release = etnaviv_gem_shmem_release,
+	.vmap = etnaviv_gem_vmap_impl,
 };
 
 void etnaviv_gem_free_object(struct drm_gem_object *obj)
@@ -868,6 +881,7 @@ static void etnaviv_gem_userptr_release(struct etnaviv_gem_object *etnaviv_obj)
 static const struct etnaviv_gem_ops etnaviv_gem_userptr_ops = {
 	.get_pages = etnaviv_gem_userptr_get_pages,
 	.release = etnaviv_gem_userptr_release,
+	.vmap = etnaviv_gem_vmap_impl,
 };
 
 int etnaviv_gem_new_userptr(struct drm_device *dev, struct drm_file *file,

drivers/gpu/drm/etnaviv/etnaviv_gem.h

@@ -78,6 +78,7 @@ struct etnaviv_gem_object *to_etnaviv_bo(struct drm_gem_object *obj)
 struct etnaviv_gem_ops {
 	int (*get_pages)(struct etnaviv_gem_object *);
 	void (*release)(struct etnaviv_gem_object *);
+	void *(*vmap)(struct etnaviv_gem_object *);
 };
 
 static inline bool is_active(struct etnaviv_gem_object *etnaviv_obj)

drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c

@@ -77,9 +77,17 @@ static void etnaviv_gem_prime_release(struct etnaviv_gem_object *etnaviv_obj)
 	drm_prime_gem_destroy(&etnaviv_obj->base, etnaviv_obj->sgt);
 }
 
+static void *etnaviv_gem_prime_vmap_impl(struct etnaviv_gem_object *etnaviv_obj)
+{
+	lockdep_assert_held(&etnaviv_obj->lock);
+
+	return dma_buf_vmap(etnaviv_obj->base.import_attach->dmabuf);
+}
+
 static const struct etnaviv_gem_ops etnaviv_gem_prime_ops = {
 	/* .get_pages should never be called */
 	.release = etnaviv_gem_prime_release,
+	.vmap = etnaviv_gem_prime_vmap_impl,
 };
 
 struct drm_gem_object *etnaviv_gem_prime_import_sg_table(struct drm_device *dev,