[PATCH v4 0/5] bcm2835: auxiliar device support for spi

[Martin Sperl]

> On 16.09.2015, at 06:11, Stephen Warren <swarren at wwwdotorg.org> wrote:
> I believe it's legitimate for a compatible property to include a
> particular value (e.g. ns16550) if and only if a driver that knows
> solely about that compatible value (i.e. just the 16550 standard
> registers) can operate the HW without issue. I don't believe that's true
> in this case since the aux enable HW bit must be programmed and does not
> exist in standard 16550 HW block.

But following that argument it would have also been “acceptable” to define 
the compatible=“regmap" approach for this auxiliar register set,
which I used in V2...

But now that we got the clock approach it works even better...