| Message ID | 20241015-dma3-mp25-updates-v2-4-b63e21556ec8@foss.st.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | STM32 DMA3 updates for STM32MP25 | expand |
On Tue, Oct 15, 2024 at 02:14:40PM +0200, Amelie Delaunay wrote: > stm32-dma3 driver refactors the linked-list in order to address the memory > with the highest possible data width. You are still talking about driver... > It means that it can introduce up to 2 linked-list items. One with a > transfer length multiple of channel maximum burst length and so with the > highest possible data width. And an extra one with the latest bytes, with > lower data width. > Some devices (e.g. FMC ECC) don't support having several transfers instead > of only one. > So add the possibility to prevent these additional transfers, by setting > bit 17 of the 'DMA transfer requirements' bit mask. Some devices require single transfers. That's about all you need to say. > > Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com> > --- > 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 >
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
stm32-dma3 driver refactors the linked-list in order to address the memory with the highest possible data width. It means that it can introduce up to 2 linked-list items. One with a transfer length multiple of channel maximum burst length and so with the highest possible data width. And an extra one with the latest bytes, with lower data width. Some devices (e.g. FMC ECC) don't support having several transfers instead of only one. So add the possibility to prevent these 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 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(+)