diff options
| author | Amelie Delaunay | 2021-06-24 11:39:58 +0200 |
|---|---|---|
| committer | Vinod Koul | 2021-07-28 12:39:48 +0530 |
| commit | ef94b0413bf4e0d328989fecf5b773e82c8794ac (patch) | |
| tree | bceded591a739a7b89e2040db0e048db931cca33 /Documentation/devicetree/bindings/dma | |
| parent | af2eec750281e581a16b6449b83ce5e994b79d89 (diff) | |
dt-bindings: dma: add alternative REQ/ACK protocol selection in stm32-dma
Default REQ/ACK protocol consists in maintaining ACK signal up to the
removal of REQuest and the transfer completion.
In case of alternative REQ/ACK protocol, ACK de-assertion does not wait the
removal of the REQuest, but only the transfer completion.
Due to a possible DMA stream lock when transferring data to/from STM32
USART/UART, this new bindings allow to select this alternative protocol in
device tree, especially for STM32 USART/UART nodes.
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210624093959.142265-2-amelie.delaunay@foss.st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'Documentation/devicetree/bindings/dma')
| -rw-r--r-- | Documentation/devicetree/bindings/dma/st,stm32-dma.yaml | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/dma/st,stm32-dma.yaml b/Documentation/devicetree/bindings/dma/st,stm32-dma.yaml index 2a5325f480f6..4bf676fd25dc 100644 --- a/Documentation/devicetree/bindings/dma/st,stm32-dma.yaml +++ b/Documentation/devicetree/bindings/dma/st,stm32-dma.yaml @@ -40,6 +40,13 @@ description: | 0x0: FIFO mode with threshold selectable with bit 0-1 0x1: Direct mode: each DMA request immediately initiates a transfer from/to the memory, FIFO is bypassed. + -bit 4: alternative DMA request/acknowledge protocol + 0x0: Use standard DMA ACK management, where ACK signal is maintained + up to the removal of request and transfer completion + 0x1: Use alternative DMA ACK management, where ACK de-assertion does + not wait for the de-assertion of the REQuest, ACK is only managed + by transfer completion. This must only be used on channels + managing transfers for STM32 USART/UART. maintainers: |