Document DMA_ATTR_CPU_CACHE_CLEAN as implemented in the
previous patch.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 Documentation/core-api/dma-attributes.rst | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/core-api/dma-attributes.rst b/Documentation/core-api/dma-attributes.rst
index 0bdc2be65e57..1d7bfad73b1c 100644
--- a/Documentation/core-api/dma-attributes.rst
+++ b/Documentation/core-api/dma-attributes.rst
@@ -148,3 +148,12 @@ DMA_ATTR_MMIO is appropriate.
 For architectures that require cache flushing for DMA coherence
 DMA_ATTR_MMIO will not perform any cache flushing. The address
 provided must never be mapped cacheable into the CPU.
+
+DMA_ATTR_CPU_CACHE_CLEAN
+------------------------
+
+This attribute indicates the CPU will not dirty any cacheline overlapping this
+DMA_FROM_DEVICE/DMA_BIDIRECTIONAL buffer while it is mapped. This allows
+multiple small buffers to safely share a cacheline without risk of data
+corruption, suppressing DMA debug warnings about overlapping mappings.
+All mappings sharing a cacheline should have this attribute.
-- 
MST