On Fri, Jul 23, 2021 at 06:44:04PM +0100, Jonathan Cameron wrote:
> Mark Brown <broonie@kernel.org> wrote:

> > > @Mark.  This has come up a few times recently.  Are we now safe to assume
> > > that regmap will always copy data when used with SPI and hence we no
> > > longer need to ensure DMA safe buffers?     

> > Only for single register I/O, I'd not assume that for things like raw
> > I/O.

> Thanks for the confirmation.  So in this driver that means we
> need DMA safe buffers for the regmap_bulk_ calls.  Easiest approach
> is probably to use a __cacheline_aligned buffer at the end of the
> iio_priv() structure.

Yeah, it might be fine depending on the bus/format type but it's not
something you can generally assume.