linux-kernel - Re: [RFC PATCH 2/2] mfd: syscon: allow reset control for syscon devices

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: <ff70222596646757cbd6e2f24aadf3247183061d.camel@codeconstruct.com.au>
Date:   Wed, 07 Dec 2022 15:56:42 +0800
From:   Jeremy Kerr <jk@...econstruct.com.au>
To:     Arnd Bergmann <arnd@...db.de>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lee Jones <lee@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Subject: Re: [RFC PATCH 2/2] mfd: syscon: allow reset control for syscon
 devices

Hi Arnd,

Thanks for taking a look a this. Just a question about the early
approach; I'm not too familiar with the internals of the syscon/regmap
infrastructure:

> > reset_controller_register() only initializes a few fields in the
> > passed rcdev structure and adds it to a static list under a static
> > mutex, so there's not much of a limit.
> 
> Ok, in that case I think we should at least leave the option of
> doing the reset from an early syscon as well.

OK, sounds good - I'll add a direct of_reset_control_get_<variant>() in
the early of_syscon_register path, which should work in a similar way to
the clocks properties.

However: this may conflict with the later platform_device syscon; if the
late syscon tries to of_reset_control_get_exclusive() the same reset
controller (because it's the same syscon node), that will (of course)
fail.

Hence a question about the syscon infrastructure: how are the late- and
early- syscon registrations supposed to interact? Should I allow for
there to be two syscons registered (one through of_syscon_register(),
the other through the platform device probe), or do we expect that to
never happen?

In case of the former, I can just grab a shared handle to the reset
controller instead, but I want to make sure that's the correct thing to do.

Cheers,

Jeremy