linux-kernel - Re: [PATCH v3 12/15] pinctrl: allow to mark pin functions as requestable GPIOs

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: <CAMRc=MeVOEFkdqf+SwQ-a=7ZPvpoerb4G_kn-aZgNLR3aTTUog@mail.gmail.com>
Date: Wed, 30 Jul 2025 14:53:37 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Linus Walleij <linus.walleij@...aro.org>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, Alexey Klimov <alexey.klimov@...aro.org>, 
	Lorenzo Bianconi <lorenzo@...nel.org>, Sean Wang <sean.wang@...nel.org>, 
	Matthias Brugger <matthias.bgg@...il.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Paul Cercueil <paul@...pouillou.net>, Kees Cook <kees@...nel.org>, 
	Andy Shevchenko <andy@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	David Hildenbrand <david@...hat.com>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka <vbabka@...e.cz>, 
	Mike Rapoport <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>, 
	Dong Aisheng <aisheng.dong@....com>, Fabio Estevam <festevam@...il.com>, 
	Shawn Guo <shawnguo@...nel.org>, Jacky Bai <ping.bai@....com>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, NXP S32 Linux Team <s32@....com>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Tony Lindgren <tony@...mide.com>, 
	Haojian Zhuang <haojian.zhuang@...aro.org>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, linux-mediatek@...ts.infradead.org, 
	linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org, 
	linux-hardening@...r.kernel.org, linux-mm@...ck.org, imx@...ts.linux.dev, 
	linux-omap@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v3 12/15] pinctrl: allow to mark pin functions as
 requestable GPIOs

On Wed, Jul 30, 2025 at 2:50 PM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Wed, Jul 30, 2025 at 11:54 AM Bartosz Golaszewski <brgl@...ev.pl> wrote:
> >
> > On Thu, Jul 24, 2025 at 2:22 PM Andy Shevchenko
> > <andy.shevchenko@...il.com> wrote:
> > >
> > > >  struct pinfunction {
> > > >         const char *name;
> > > >         const char * const *groups;
> > > >         size_t ngroups;
> > > > +       unsigned long flags;
> > >
> > > Not sure we need this. If the function is GPIO, pin control already
> > > knows about this. The pin muxing has gpio request / release callbacks
> > > that change the state. Why do we need an additional flag(s)?
> > >
> >
> > I'm not following, how does the pin controller know that the function
> > is GPIO exactly, other than by the bit set in this field?
>
> AFAICS the gpio_owner != NULL means that. No need to have a duplicate
> of this information.
>

No, that's not at all what this series does... gpio_owner is the
consumer label of a pin used by the GPIOLIB framework. The flag I'm
introducing it telling the pinctrl core - before GPIOLIB is ever
involved - that *this pin can be requested as a GPIO by GPIOLIB*. It's
the other way around - without knowing this, for strict pinmuxers,
GPIOLIB would never be able to request this pin if it was muxed to a
function (even if the function is called "GPIO").

Bart