On Mon, May 11, 2020 at 05:10:16AM +0300, Serge Semin wrote:

> Alas linearizing the SPI messages won't help in this case because the DW DMA
> driver will split it into the max transaction chunks anyway.

That sounds like you need to also impose a limit on the maximum message
size as well then, with that you should be able to handle messages up
to whatever that limit is.  There's code for that bit already, so long
as the limit is not too low it should be fine for most devices and
client drivers can see the limit so they can be updated to work with it
if needed.