[PATCH 1/2] drm: rockchip: Don't pass DRM fake offset to dma-api

["Ørjan Eide" <orjan.eide@arm.com>]

Set vm_pgoff to 0 after using it to look up the GEM node, before passing
it on rockchip_gem_mmap_buf() where the offset must be from the start of
the buffer.

Passing in the fake offset currently works because the
dma_mmap_attrs implementation that is used for this device,
arm_iommu_mmap_attrs, ignores the offset completely.

Signed-off-by: Ørjan Eide <orjan.eide@arm.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index 7ca8799e..69f01c3 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -94,6 +94,11 @@ int rockchip_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 		return -EACCES;
 	}
 
+	/* 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;
+
 	obj = container_of(node, struct drm_gem_object, vma_node);
 	ret = rockchip_gem_mmap_buf(obj, vma);
 
-- 
1.9.1