gbm: Export a getter for per plane handles

v2: Make the error return be -1 instead of 0 because I think 0 is
actually valid.

v3: Set errno to EINVAL when the specified plane is above the total
planes. (Jason Ekstrand)
Return the bo's handle if there is no image ie. for dumb images like cursor (Daniel)

v4:
- Add assertions about plane == 0 (Jason)
- Add a comment about new restriction on planar dumb bo which is not an
earlier patch in the series.
- Correctly refactor from v2 in this patch; it ended up rebased into the
wrong patch.

Signed-off-by: Ben Widawsky <[email protected]>
Reviewed-by: Jason Ekstrand <[email protected]>
Acked-by: Daniel Stone <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/gbm/main/gbm.h b/src/gbm/main/gbm.h
index 203a2363579..67548206c40 100644
--- a/src/gbm/main/gbm.h
+++ b/src/gbm/main/gbm.h
@@ -318,6 +318,9 @@ gbm_bo_get_fd(struct gbm_bo *bo);
 int
 gbm_bo_get_plane_count(struct gbm_bo *bo);
 
+union gbm_bo_handle
+gbm_bo_get_handle_for_plane(struct gbm_bo *bo, int plane);
+
 int
 gbm_bo_write(struct gbm_bo *bo, const void *buf, size_t count);