Re: [PATCH 01/13] dt-bindings: i2c: nomadik: add timeout-usecs property bindings

Théo Lebrun
2024-02-21T16:58:15Z

Hello,

On Mon Feb 19, 2024 at 3:29 PM CET, Théo Lebrun wrote:
> On Mon Feb 19, 2024 at 3:06 PM CET, Linus Walleij wrote:
> > On Fri, Feb 16, 2024 at 10:16 AM Théo Lebrun <theo.lebrun@bootlin.com> wrote:
> > > i2c-mpc (fsl,timeout) and i2c-gpio (i2c-gpio,timeout-ms). I agree this
> > > prop has no reason to be compatible-specific.
> > >
> > > Feedback from dt-bindings and I2C host maintainers would be useful: what
> > > should the property be named? Having the unit makes it self-descriptive,
> > > which sounds like a good idea to me. timeout-usecs, timeout-us, another
> > > option?
> >
> > Use i2c-transfer-timeout-ms in my opinion, so it us crystal clear
> > what that property is for.
>
> Using µs (microseconds) would be OK? I'm not sure yet about the exact
> timeout desired but a one millisecond granularity might not be enough
> for the Mobileye usecase.
>
> Expect incoming patches to use the I2C controller in Fast Mode Plus
> (1Mbps) and High Speed Mode (3.4Mbps). Gotta go fast!
>
> > As Rob mentioned this isn't in the kernel schemas but in dtschema, so
> > you need to patch this:
> > https://github.com/robherring/dt-schema
>
> Indeed. The other question if we do microseconds is the
> suffix: -us, -usecs, -microseconds, etc? I picked -usecs for my v1, but
> a grep tells me I am the only user of this suffix. -us is much more
> common.
>
> BTW i2c-controller.yaml already has a µs timeout:
> i2c-scl-clk-low-timeout-us

Note: I've sent a draft patch to dt-schema. See:
https://github.com/devicetree-org/dt-schema/pull/129

Feedback from I2C maintainers would confirm or infirm that this goes in
the right direction.

Thanks,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering