Re: [PATCH 1/2] dt-bindings: pinctrl: renesas,r9a09g077: Document pin configuration properties

[Lad, Prabhakar]

Hi All,

On Mon, Jan 19, 2026 at 12:10 AM Linus Walleij <linusw@xxxxxxxxxx> wrote:
>
> Hi Lad,
>
> I think this back-and-forth must be a bit stressful. Sorry about that.
>
> On Wed, Jan 14, 2026 at 9:53 PM Lad, Prabhakar
> <prabhakar.csengg@xxxxxxxxx> wrote:
>
> > > > > > > +      renesas,drive-strength:
> > > > > > > +        description:
> > > > > > > +          Drive strength configuration value. Valid values are 0 to 3, representing
> > > > > > > +          increasing drive strength from low, medium, high and ultra high.
> > > > > >
>
> > I got the feedback from the HW team "The RZ/T2H drive strength
> > (driving ability) is expressed using abstract levels such as Low,
> > Middle, and High. These values do not correspond directly to specific
> > mA units.
>
> But they do correspond to *something* electrical inside the
> silicon do they not? Then what is that?
>
> I think it is just 1, 2, 3 or 4 driver stages.
>
> > To determine how much current the pin can actually drive,
> > the engineer must refer to the electrical characteristics table.
> > Therefore, the drive strength in RZ/T2H is a parameter that switches
> > the internal output transistor mode rather than directly representing
> > a physical drive current.
> >
> > Consequently, expressing RZ/T2H drive strength in milli- or
> > micro-amps, as suggested by the reviewer, is inappropriate. To
> > accurately reflect the SoC's hardware specification, introducing a
> > custom property is essential."
>
Sorry for the confusion , there was a miscommunication regarding the
specs, but it’s all been sorted out. The drive-strength settings on
this chip are 2.5/5/9/11.8 mA, I will represent them using the
drive-strength-microamp DT property and send a new version.

Cheers,
Prabhakar