Re: [PATCH 1/5] dt-bindings: dma: dw: Add optional DMA-channels mask cell support

Rob Herring
2020-07-31T22:42:17Z

On Thu, 30 Jul 2020 18:45:41 +0300, Serge Semin wrote:
> Each DW DMA controller channel can be synthesized with different
> parameters like maximum burst-length, multi-block support, maximum data
> width, etc. Most of these parameters determine the DW DMAC channels
> performance in its own aspect. On the other hand these parameters can
> be implicitly responsible for the channels performance degradation
> (for instance multi-block support is a very useful feature, but having
> it disabled during the DW DMAC synthesize will provide a more optimized
> core). Since DMA slave devices may have critical dependency on the DMA
> engine performance, let's provide a way for the slave devices to have
> the DMA-channels allocated from a pool of the channels, which according
> to the system engineer fulfill their performance requirements.
>
> The pool is determined by a mask optionally specified in the fifth
> DMA-cell of the DMA DT-property. If the fifth cell is omitted from the
> phandle arguments or the mask is zero, then the allocation will be
> performed from a set of all channels provided by the DMA controller.
>
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> ---
> .../devicetree/bindings/dma/snps,dma-spear1340.yaml | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>

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