[PATCH v4 2/4] spi: Split spi message into max_dma_len size chunks

[kernel at martin.sperl.org]

> On 12.04.2019, at 11:47, Mark Brown <broonie at kernel.org> wrote:
> 
> 
>> In a previous version of this I suggested to Meghana to put this in the
>> driver, but Mark wanted it in the core.
> 
> If we want to do this at a lower level the DMA code could hide this
> limitation from the upper layers; presumably the SPI driver isn't the
> only thing that might run into this.

For clarification:
There is a register of the SPI controller where you have to configure the
number of bytes that it will request via DMA (primarily support transfers
that are not a multiple of 4 - the data is transferred by DMA as words).
So it is not really related to the general DMA implementation but to the
DMA (request) support of the SPI controller.

Martin