[PATCH v3 0/6] STM32 DMA-MDMA chaining feature

[Amelie Delaunay]

Please drop this malformed patchset, I'll send a new one.

On 7/19/22 17:31, Amelie Delaunay wrote:
> This patchset (re)introduces STM32 DMA-MDMA chaining feature.
> 
> As the DMA is not able to generate convenient burst transfer on the DDR,
> it penalises the AXI bus when accessing the DDR. While it accesses
> optimally the SRAM. The DMA-MDMA chaining then consists in having an SRAM
> buffer between DMA and MDMA, so the DMA deals with peripheral and SRAM,
> and the MDMA with SRAM and DDR.
> 
> The feature relies on the fact that DMA channel Transfer Complete signal
> can trigger a MDMA channel transfer and MDMA can clear the DMA request by
> writing to DMA Interrupt Clear register.
> 
> A deeper introduction can be found in patch 1.
> 
> Previous implementation [1] has been dropped as nacked.
> Unlike this previous implementation (where all the stuff was embedded in
> stm32-dma driver), the user (in peripheral drivers using dma) has now to
> configure the MDMA channel.
> 
> [1] https://lore.kernel.org/lkml/1538139715-24406-1-git-send-email-pierre-yves.mordret@st.com/
> 
> Changes in v3:
> - introduce two prior patches to help readibility
> - fix stm32-dma struct stm32_dma_mdma_config documentation
> 
> Changes in v2:
> - wrap to 80-column limit for documentation
> - add an entry for this documentation in index.rst
> - use simple table instead of csv-table in documentation
> 
> 
> Amelie Delaunay (6):
>    dmaengine: stm32-dma: introduce 3 helpers to address channel flags
>    dmaengine: stm32-dma: use bitfield helpers
>    docs: arm: stm32: introduce STM32 DMA-MDMA chaining feature
>    dmaengine: stm32-dmamux: set dmamux channel id in dma features
>      bitfield
>    dmaengine: stm32-dma: add support to trigger STM32 MDMA
>    dmaengine: stm32-mdma: add support to be triggered by STM32 DMA
> 
>   Documentation/arm/index.rst                   |   1 +
>   .../arm/stm32/stm32-dma-mdma-chaining.rst     | 415 ++++++++++++++++++
>   drivers/dma/stm32-dma.c                       | 136 +++---
>   drivers/dma/stm32-dmamux.c                    |   2 +-
>   drivers/dma/stm32-mdma.c                      |  70 ++-
>   5 files changed, 569 insertions(+), 55 deletions(-)
>   create mode 100644 Documentation/arm/stm32/stm32-dma-mdma-chaining.rst
>