Re: regmap I3C support

[Guenter Roeck]

On 11/13/24 06:41, Mark Brown wrote:
> On Wed, Nov 13, 2024 at 06:15:38AM -0800, Guenter Roeck wrote:
> > On 11/13/24 06:01, Mark Brown wrote:
>
> > > Don't these drivers end up with the same miserable problems with
> > > dependencies on variations of things being configured built in and
> > > modules anyway that mean we build separate SPI and I2C bus wrappers for
> > > the same case with devices that do both I2C and SPI?
>
> > Not really. There is no equivalent to module_i3c_i2c_driver() to handle both
> > I2C and SPI variants of a chip. Also, SPI and I2C/I3C are not interdependent,
>
> Sure, but lots of drivers were open coding an equivalent of that
> (possibly some still do).
>
> > while I3C automatically selects I2C. That means it does make sense to handle
> > I2C and I3C in the same driver, but not I2C and SPI.
>
> In terms of the devices they're very much the same and interdependent -
> it's generally one IP block and one set of pins that's doing both I2C
> and SPI, with nothing software visible different.  If I3C selects I2C
> then that does eliminate some of the problem space, I can't remember the
> speciifcs of how people (I think mainly randconfig people?) were
> breaking things.  You at least have I2C=y I3C=m which means that
> dependencies have to force the users modular.
>
> > Sure, separate wrappers can be used, but that makes module_i3c_i2c_driver()
> > pointless.
>
> That's kind of my question.  If we are going to have this sort of stuff
> we should also have it for I2C and SPI since it's such a common pattern.

I'll take that as "we are not going to provide a dummy regmap i3c registration
function". Thanks, that is all I needed to know.

Guenter