Re: [PATCH] gpio: add GPO driver for PCA9570

[Michael Walle]

Hi,

Am 2020-06-24 16:52, schrieb Andy Shevchenko:
> On Wed, Jun 24, 2020 at 4:46 PM Michael Walle <michael@xxxxxxxx> wrote:

[..]

> > So you just write one byte of data (or you might repeat it, but
> > that is just as if you start a new i2c transaction, just that
> > you save the i2c addressing).
>
> You can write the same value twice.
> It means that the first byte can represent the register address. But
> it's still too volatile.

In this case the output pin will hold the value of the "fake" address
register for a short period of time. No?

> Perhaps regmap can gain something like register-less communication.

I don't know if that is worth it (and if that is an intended use of
regmap).

-michael