minigbm: add drv_bo_flush

As an optimization, we would like to separate buffer flush/writeback
and unmap. This patch adds the appropriate entry point in our
internal driver API. Overall, the proposed flow is:

	- drv_bo_map(..) creates a mapping and associated metadata
	- drv_bo_flush(..) writes memory from any cache or temporary
          buffer back to memory
        - drv_bo_unmap(..) flushes, and frees the mapping and
	  associated metadata.

The drv_bo_flush function just does some sanity checks on
the map data at this point, but otherwise is a no-op.

BUG=chromium:764871
TEST=gbmtest, mmap_test -g on eve

Change-Id: If306f066a76bc5e0943c1170e2d6933fa5630eff
Reviewed-on: https://chromium-review.googlesource.com/668218
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>

3 files changed, 19 insertions, 5 deletions

diff --git a/drv.c b/drv.c
index b43b771..fab9958 100644
--- a/drv.c
+++ b/drv.c
@@ -411,10 +411,9 @@ success:
 
 int drv_bo_unmap(struct bo *bo, struct map_info *data)
 {
-	int ret = 0;
-
-	assert(data);
-	assert(data->refcount >= 0);
+	int ret = drv_bo_flush(bo, data);
+	if (ret)
+		return ret;
 
 	pthread_mutex_lock(&bo->drv->driver_lock);
 
@@ -429,6 +428,18 @@ int drv_bo_unmap(struct bo *bo, struct map_info *data)
 	return ret;
 }
 
+int drv_bo_flush(struct bo *bo, struct map_info *data)
+{
+	int ret = 0;
+	assert(data);
+	assert(data->refcount >= 0);
+
+	if (bo->drv->backend->bo_flush)
+		ret = bo->drv->backend->bo_flush(bo, data);
+
+	return ret;
+}
+
 uint32_t drv_bo_get_width(struct bo *bo)
 {
 	return bo->width;
diff --git a/drv.h b/drv.h
index e4678a1..f9a7a87 100644
--- a/drv.h
+++ b/drv.h
@@ -113,7 +113,9 @@ struct bo *drv_bo_import(struct driver *drv, struct drv_import_fd_data *data);
 void *drv_bo_map(struct bo *bo, uint32_t x, uint32_t y, uint32_t width, uint32_t height,
 		 uint32_t flags, struct map_info **map_data, size_t plane);
 
-int drv_bo_unmap(struct bo *bo, struct map_info *map_data);
+int drv_bo_unmap(struct bo *bo, struct map_info *data);
+
+int drv_bo_flush(struct bo *bo, struct map_info *data);
 
 uint32_t drv_bo_get_width(struct bo *bo);
 
diff --git a/drv_priv.h b/drv_priv.h
index fed6c19..e7b2d25 100644
--- a/drv_priv.h
+++ b/drv_priv.h
@@ -77,6 +77,7 @@ struct backend {
 	int (*bo_import)(struct bo *bo, struct drv_import_fd_data *data);
 	void *(*bo_map)(struct bo *bo, struct map_info *data, size_t plane, int prot);
 	int (*bo_unmap)(struct bo *bo, struct map_info *data);
+	int (*bo_flush)(struct bo *bo, struct map_info *data);
 	uint32_t (*resolve_format)(uint32_t format, uint64_t usage);
 };