linux-kernel - Re: [PATCH v4 7/8] soc: renesas: Add support for Renesas RZ/N1 GPIO Interrupt Multiplexer

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

Message-ID: <20251015082103.7907e019@bootlin.com>
Date: Wed, 15 Oct 2025 08:21:03 +0200
From: Herve Codina <herve.codina@...tlin.com>
To: Linus Walleij <linus.walleij@...aro.org>, Wolfram Sang
 <wsa+renesas@...g-engineering.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Hoan Tran
 <hoan@...amperecomputing.com>, Bartosz Golaszewski <brgl@...ev.pl>, Rob
 Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor
 Dooley <conor+dt@...nel.org>, Geert Uytterhoeven <geert+renesas@...der.be>,
 Magnus Damm <magnus.damm@...il.com>, Saravana Kannan
 <saravanak@...gle.com>, Serge Semin <fancer.lancer@...il.com>, Phil
 Edworthy <phil.edworthy@...esas.com>, linux-gpio@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-renesas-soc@...r.kernel.org, Pascal Eberhard
 <pascal.eberhard@...com>, Miquel Raynal <miquel.raynal@...tlin.com>, Thomas
 Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v4 7/8] soc: renesas: Add support for Renesas RZ/N1 GPIO
 Interrupt Multiplexer

Hi Linus, Wolfram,

On Tue, 14 Oct 2025 22:13:50 +0200
Linus Walleij <linus.walleij@...aro.org> wrote:

> On Tue, Oct 14, 2025 at 4:30 PM Wolfram Sang
> <wsa+renesas@...g-engineering.com> wrote:
> 
> > Because the HW design kind of suggests it, I'd think. The GPIO
> > controller is a standard Synopsis one ("snps,dw-apb-gpio") without any
> > extras. The GPIOMUX (which is extra) is according to the docs part of
> > the system controller with a dedicated set of registers. Luckily,
> > self-contained and not mangled with other functionality.  
> 
> Aha I see. If this is so tightly coupled with the Synopsis
> designware GPIO then it should be mentioned in the commit
> I guess. Also:
> 
> config RZN1_IRQMUX
>        bool "Renesas RZ/N1 GPIO IRQ multiplexer support" if COMPILE_TEST
> 
> +      depends on GPIO_DWAPB || COMPILE_TEST
> 
> ?
> 
> I understand that it is convenient to make this a separate driver.
> 
> I'm not sure it is the right thing to do, but it's no a hill I want to
> die on so if everyone else thinks I'm wrong, I can just shut up
> about it, it's not like this driver is a big obstacle or anything.
> 
> Yours,
> Linus Walleij

I don't think the mux should depends on GPIO_DWAPB (the gpio controller).

Also, several gpio controller instances are connected to the mux.

The 96 GPIOs connected to the mux come from 3 GPIO controller instances (32
gpios per instance). I don't think it makes sense to have the mux handled by
the gpio driver itself. It could have make sense if 3 muxes were available,
one per gpio controller but this is not the case.

As Wolfram said, the mux is an hardware component really outside of the
GPIO controller IPs.

Best regards,
Hervé