[PATCH v12 7/7] Documentation: dmaengine: Document new dma_vec API

Paul Cercueil
2024-06-20T12:28:48Z

Document the dmaengine_prep_peripheral_dma_vec() API function, the
device_prep_peripheral_dma_vec() backend function, and the dma_vec
struct.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>

---
v11: New patch
---
Documentation/driver-api/dmaengine/client.rst | 9 +++++++++
Documentation/driver-api/dmaengine/provider.rst | 10 ++++++++++
2 files changed, 19 insertions(+)

diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst
index ecf139f73da4..d491e385d61a 100644
--- a/Documentation/driver-api/dmaengine/client.rst
+++ b/Documentation/driver-api/dmaengine/client.rst
@@ -80,6 +80,10 @@ The details of these operations are:

- slave_sg: DMA a list of scatter gather buffers from/to a peripheral

+ - peripheral_dma_vec: DMA an array of scatter gather buffers from/to a
+ peripheral. Similar to slave_sg, but uses an array of dma_vec
+ structures instead of a scatterlist.
+
- dma_cyclic: Perform a cyclic DMA operation from/to a peripheral till the
operation is explicitly stopped.

@@ -102,6 +106,11 @@ The details of these operations are:
unsigned int sg_len, enum dma_data_direction direction,
unsigned long flags);

+ struct dma_async_tx_descriptor *dmaengine_prep_peripheral_dma_vec(
+ struct dma_chan *chan, const struct dma_vec *vecs,
+ size_t nents, enum dma_data_direction direction,
+ unsigned long flags);
+
struct dma_async_tx_descriptor *dmaengine_prep_dma_cyclic(
struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
size_t period_len, enum dma_data_direction direction);
diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst
index ceac2a300e32..3085f8b460fa 100644
--- a/Documentation/driver-api/dmaengine/provider.rst
+++ b/Documentation/driver-api/dmaengine/provider.rst
@@ -433,6 +433,12 @@ supported.
- residue: Provides the residue bytes of the transfer for those that
support residue.

+- ``device_prep_peripheral_dma_vec``
+
+ - Similar to ``device_prep_slave_sg``, but it takes a pointer to a
+ array of ``dma_vec`` structures, which (in the long run) will replace
+ scatterlists.
+
- ``device_issue_pending``

- Takes the first transaction descriptor in the pending queue,
@@ -544,6 +550,10 @@ dma_cookie_t
- Not really relevant any more since the introduction of ``virt-dma``
that abstracts it away.

+dma_vec
+
+- A small structure that contains a DMA address and length.
+
DMA_CTRL_ACK

- If clear, the descriptor cannot be reused by provider until the
--
2.43.0