[v3] STM32 DMA3 updates for STM32MP25

[PATCH v3 4/9] dt-bindings: dma: stm32-dma3: prevent additional transfers

Posted by Amelie Delaunay 1 month, 1 week ago

Some devices require a single transfer. For example, reading FMC ECC status
registers does not support multiple transfers.
Add the possibility to prevent additional transfers, by setting bit 17 of
the 'DMA transfer requirements' bit mask.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
---
Changes in v3:
- Refine commit description as per Rob's suggestion.
Changes in v2:
- Reword commit title/message/content as per Rob's suggestion.
---
 Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml b/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml
index 5484848735f8ac3d2050104bbab1d986e82ba6a7..36f9fe860eb990e6caccedd31460ee6993772a35 100644
--- a/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml
+++ b/Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml
@@ -99,6 +99,9 @@ properties:
         -bit 16: Prevent packing/unpacking mode
           0x0: pack/unpack enabled when source data width/burst != destination data width/burst
           0x1: memory data width/burst forced to peripheral data width/burst to prevent pack/unpack
+        -bit 17: Prevent additional transfers due to linked-list refactoring
+          0x0: don't prevent additional transfers for optimal performance
+          0x1: prevent additional transfer to accommodate user constraints such as single transfer
 
 required:
   - compatible

-- 
2.25.1

Re: [PATCH v3 4/9] dt-bindings: dma: stm32-dma3: prevent additional transfers

Posted by Rob Herring (Arm) 1 month, 1 week ago

On Wed, 16 Oct 2024 14:39:56 +0200, Amelie Delaunay wrote:
> Some devices require a single transfer. For example, reading FMC ECC status
> registers does not support multiple transfers.
> Add the possibility to prevent additional transfers, by setting bit 17 of
> the 'DMA transfer requirements' bit mask.
> 
> Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
> ---
> Changes in v3:
> - Refine commit description as per Rob's suggestion.
> Changes in v2:
> - Reword commit title/message/content as per Rob's suggestion.
> ---
>  Documentation/devicetree/bindings/dma/stm32/st,stm32-dma3.yaml | 3 +++
>  1 file changed, 3 insertions(+)
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>