linux-kernel - Re: [PATCH 2/2] arm64: dts: renesas: r9a09g047e57-smarc: Add overlay for P3T1085UK-ARD

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <aRyiQJsu6gob3Gf9@shikoro>
Date: Tue, 18 Nov 2025 17:43:44 +0100
From: Wolfram Sang <wsa+renesas@...g-engineering.com>
To: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
Cc: tomm.merciai@...il.com, linux-renesas-soc@...r.kernel.org,
	biju.das.jz@...renesas.com,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] arm64: dts: renesas: r9a09g047e57-smarc: Add overlay
 for P3T1085UK-ARD

Hi Tommaso,

> +/*
> + * #define I3C_BUS_MODE_PURE 1 (for I3C bus mode pure - default)
> + * #define I3C_BUS_MODE_PURE 0 (for I3C bus mode mixed-fast)
> + */
> +#define I3C_BUS_MODE_PURE	1

Sorry, but I really think this is configuration and not hardware
description. The board has only I3C capable devices, so unless you
connect more devices externally, you can always use pure-i3c-mode.
Enforcing mixed-mode is only for debugging.

> +
> +#if I3C_BUS_MODE_PURE
> +&i3c {
> +	i2c-scl-hz = <400000>;
> +	i3c-scl-hz = <12500000>;
> +	status = "okay";
> +};

So, the above is all that is needed. Which is the basic enablement for
the I3C bus in general. I mean, auto-detecting devices is a key feature
of I3C :) Which basically means IMHO that this overlay is superfluous.

> +#else /* I3C_BUS_MODE_MIXED_FAST */
> +&i3c {
> +	status = "okay";
> +
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +
> +	i2c-scl-hz = <400000>;
> +	i3c-scl-hz = <12500000>;

Despite this else block being debug only...

> +
> +	eeprom@1a {
> +		compatible = "atmel,24c02";
> +		reg = <0x1a 0 (I2C_FM | I2C_FILTER)>;
> +	};

... there is no device listening to 0x1a on this board? What do you see
there? Did I forget something?

> +
> +	/* U2 */
> +	temperature-sensor@48 {
> +		compatible = "nxp,p3t1085";
> +		reg = <0x48 0 (I2C_FM | I2C_FILTER)>;
> +	};
> +
> +	/* U1 NOT MOUNTED as default */
> +	temp-sense@4c {
> +		status = "disabled";
> +		compatible = "national,lm75";

Yes, mounting U1 is a hack I introduced. The compatible should be
"nxp,p3t1755" BTW. But as said, the whole MIXED_MODE block is not
hardware description, I'd say.

Happy hacking,

   Wolfram

Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)