RE: [PATCH] arm64: dts: renesas: r9a09g047e57-smarc: Reduce I2C2 clock frequency

[John Madieu]

Hi Geert,

> -----Original Message-----
> From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Sent: Monday, May 19, 2025 10:29 AM
> To: John Madieu <john.madieu.xa@xxxxxxxxxxxxxx>
> Subject: Re: [PATCH] arm64: dts: renesas: r9a09g047e57-smarc: Reduce I2C2
> clock frequency
> 
> Hi John,
> 
> On Mon, 19 May 2025 at 00:08, John Madieu <john.madieu.xa@xxxxxxxxxxxxxx>
> wrote:
> > Lower the I2C2 bus clock frequency on the RZ/G3E SMARC SoM from 1MHz
> > to 400KHz to improve compatibility with a wider range of I2C
> > peripherals. The previous 1MHz setting was too aggressive for some
> > devices on the bus, which experienced timing issues at such a frequency.
> >

Thanks for the feedback.

> 
> > --- a/arch/arm64/boot/dts/renesas/rzg3e-smarc-som.dtsi
> > +++ b/arch/arm64/boot/dts/renesas/rzg3e-smarc-som.dtsi
> > @@ -85,7 +85,7 @@ &gpu {
> >  &i2c2 {
> >         pinctrl-0 = <&i2c2_pins>;
> >         pinctrl-names = "default";
> > -       clock-frequency = <1000000>;
> > +       clock-frequency = <400000>;
> >         status = "okay";
> >
> >         raa215300: pmic@12 {
> 
> Can you please clarify which devices on this bus do not support 1 MHz?
> Or perhaps this is a board layout issue?
> 

This is mainly the case for the GreenPAK device, that is programmed to
Operate at 400KHz.

> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
> m68k.org
> 
Regards,
John