[PATCH 1/2] drm/shmem: add support for per object dma api operations

[Gurchetan Singh]

This is useful for the next patch.  Also, should we only unmap the
amount entries that we mapped with the dma-api?

Signed-off-by: Gurchetan Singh <gurchetansingh at chromium.org>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c | 16 +++++++++++-----
 include/drm/drm_gem_shmem_helper.h     | 10 ++++++++++
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 0a7e3b664bc2..d439074ad7b5 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -124,8 +124,10 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj)
 		drm_prime_gem_destroy(obj, shmem->sgt);
 	} else {
 		if (shmem->sgt) {
-			dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
-				     shmem->sgt->nents, DMA_BIDIRECTIONAL);
+			if (!shmem->skip_dma_api)
+				dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
+					     shmem->dma_map_count,
+					     DMA_BIDIRECTIONAL);
 			sg_free_table(shmem->sgt);
 			kfree(shmem->sgt);
 		}
@@ -422,8 +424,9 @@ void drm_gem_shmem_purge_locked(struct drm_gem_object *obj)
 
 	WARN_ON(!drm_gem_shmem_is_purgeable(shmem));
 
-	dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
-		     shmem->sgt->nents, DMA_BIDIRECTIONAL);
+	if (!shmem->skip_dma_api)
+		dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
+			     shmem->dma_map_count, DMA_BIDIRECTIONAL);
 	sg_free_table(shmem->sgt);
 	kfree(shmem->sgt);
 	shmem->sgt = NULL;
@@ -695,7 +698,10 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
 		goto err_put_pages;
 	}
 	/* Map the pages for use by the h/w. */
-	dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL);
+	if (!shmem->skip_dma_api)
+		shmem->dma_map_count = dma_map_sg(obj->dev->dev, sgt->sgl,
+						  sgt->nents,
+						  DMA_BIDIRECTIONAL);
 
 	shmem->sgt = sgt;
 
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 5381f0c8cf6f..2669d87cbfdd 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -101,6 +101,16 @@ struct drm_gem_shmem_object {
 	 * @map_cached: map object cached (instead of using writecombine).
 	 */
 	bool map_cached;
+
+	/**
+	 * @skip_dma_api: skip using dma api in certain places.
+	 */
+	bool skip_dma_api;
+
+	/**
+	 * @skip_dma_api: number of pages mapped by dma-api.
+	 */
+	bool dma_map_count;
 };
 
 #define to_drm_gem_shmem_obj(obj) \
-- 
2.25.1