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path: root/drivers/gpu/drm/tegra/gem.c
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Diffstat (limited to 'drivers/gpu/drm/tegra/gem.c')
-rw-r--r--drivers/gpu/drm/tegra/gem.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
index 1237df157e05e8..623768100c6a2c 100644
--- a/drivers/gpu/drm/tegra/gem.c
+++ b/drivers/gpu/drm/tegra/gem.c
@@ -60,8 +60,16 @@ static struct sg_table *tegra_bo_pin(struct device *dev, struct host1x_bo *bo,
/*
* If we've manually mapped the buffer object through the IOMMU, make
* sure to return the IOVA address of our mapping.
+ *
+ * Similarly, for buffers that have been allocated by the DMA API the
+ * physical address can be used for devices that are not attached to
+ * an IOMMU. For these devices, callers must pass a valid pointer via
+ * the @phys argument.
+ *
+ * Imported buffers were also already mapped at import time, so the
+ * existing mapping can be reused.
*/
- if (phys && obj->mm) {
+ if (phys) {
*phys = obj->iova;
return NULL;
}