On Sun, Dec 03, 2017 at 08:43:47PM +0100, Wolfram Sang wrote:

> > It's a bit different in that it's much more likely that a SPI controller
> > will actually do DMA than an I2C one since the speeds are higher and
> > there's frequent applications that do large transfers so it's more
> > likely that people will do the right thing as issues would tend to come
> > up if they don't.

> Yes, for SPI this is true. I was thinking more of regmap with its
> usage of different transport mechanisms. But I guess they should all be
> DMA safe because some of them need to be DMA safe?

Possibly.  Hopefully.  I guess we'll find out.