linux-kernel - Re: [PATCH v3 1/9] dt-bindings: misc: Describe TI FPC202 dual port controller

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: <3923123.7gsWKXV4c1@fw-rgant>
Date: Wed, 27 Nov 2024 09:20:26 +0100
From: Romain Gantois <romain.gantois@...tlin.com>
To: Conor Dooley <conor@...nel.org>
Cc: Wolfram Sang <wsa+renesas@...g-engineering.com>,
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
 Luca Ceresoli <luca.ceresoli@...tlin.com>,
 Andi Shyti <andi.shyti@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
 Derek Kiernan <derek.kiernan@....com>, Dragan Cvetic <dragan.cvetic@....com>,
 Arnd Bergmann <arnd@...db.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Mauro Carvalho Chehab <mchehab@...nel.org>,
 Linus Walleij <linus.walleij@...aro.org>,
 Bartosz Golaszewski <brgl@...ev.pl>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 Kory Maincent <kory.maincent@...tlin.com>, linux-i2c@...r.kernel.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
 linux-media@...r.kernel.org, linux-gpio@...r.kernel.org
Subject:
 Re: [PATCH v3 1/9] dt-bindings: misc: Describe TI FPC202 dual port controller

On mardi 26 novembre 2024 19:09:43 heure normale d’Europe centrale Conor Dooley wrote:
> On Tue, Nov 26, 2024 at 09:05:42AM +0100, Romain Gantois wrote:
> > Hello Conor,
...
> > 
> > But then again, you could consider that DT bindings should only describe
> > what is possible, and not only what makes sense as a use case. I don't
> > really know how to answer this question myself, so I'll refer to the
> > maintainers' opinions.
> I don't really know what how this device works, which is why I am asking
> questions. If there is no use case were someone would only wire up one
> of the downstream ports then making both required is fine. I was just
> thinking that someone might only hook devices up to one side of it and
> leave the other unused entirely. Seemed like it could serve its role
> without both sides being used based on the diagram in
> https://docs.kernel.org/i2c/i2c-address-translators.html
> unless it is not possible for the atr to share the "parent" i2c bus with
> other devices?

It is possible for the FPC202 to share it's parent bus with other devices. And I
guess you could wire up only one port and use the component as a simple
address translator and GPIO aggregator.

So indeed, requiring both ports to be described seems unnecessary.

Thanks,

-- 
Romain Gantois, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com