Linux GPIO subsystem development
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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: "Frank Wunderlich (linux)" <linux@fw-web.de>
Cc: Linus Walleij <linusw@kernel.org>,
	Bartosz Golaszewski <brgl@kernel.org>,
	Frank Wunderlich <frank-w@public-files.de>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
	frank.wunderlich@linux.dev
Subject: Re: [PATCH] gpiolib: use of_node_name if line-name is missing
Date: Thu, 17 Sep 2026 16:37:52 +0300	[thread overview]
Message-ID: <aqvtMDiqCzsxUDKw@ashevche-desk.local> (raw)
In-Reply-To: <85b0d147af3b63a6b2419b7daaf81332@fw-web.de>

On Thu, Sep 17, 2026 at 03:20:49PM +0200, Frank Wunderlich (linux) wrote:
> Am 2026-09-17 15:00, schrieb Andy Shevchenko:
> > On Thu, Sep 17, 2026 at 02:28:13PM +0200, Frank Wunderlich wrote:

...

> > > int gpiochip_add_hog(struct gpio_chip *gc, struct fwnode_handle
> > > *fwnode)
> > 
> > >  	fwnode_property_read_string(fwnode, "line-name", &name);
> > > 
> > > +	if (!name && is_of_node(fwnode))
> > > +		name = to_of_node(fwnode)->name;
> > 
> > Can we move it inside the loop? Yes, I understand that it will be
> > unnecessarily
> > called more times than required, but gpiod_hog() is called anyway in the
> > loop,
> > so I don't think it will be a big deal. With that it will allow to group
> > OF-specific code in one location.
> > 
> > >  	for (unsigned int i = 0; i < num_hogs; i++) {
> > >  		if (is_of_node(fwnode)) {
> > 
> > 		...somewhere inside this conditional...
> > 
> > >  			/*
> 
> I'm not sure what you want to achieve here (maybe only to have the
> is_of_node-condition once?, as the loop imho is only for enumerating
> multiple gpio (like "gpios = <3 0>, <4 0>;") inside one hog of_node.

The primary goal is stop spreading OF-specific code. If you have noticed the
function was also rewritten (during the move) to be fwnode agnostic, but that
was not feasible by 100%, the leftover is collected inside the mentioned loop.
That's why I really prefer to keep all OF code there.

> Here the node-name will never change (like the line-name above) and read-once
> is correct.
> But while looking at the code i also thought about these multi-gpio-hogs
> (label and output-X). Imho here something like the gpio-controllers
> "line-names" would make sense as well as something similar for the output
> (or just handling this with the GPIO_ACTIVE_HIGH/LOW param).
> 
> But if you think the part should be moved into the loop, that's no big deal.

Yes, I think that way.

-- 
With Best Regards,
Andy Shevchenko



  reply	other threads:[~2026-09-17 13:38 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-17 12:28 [PATCH] gpiolib: use of_node_name if line-name is missing Frank Wunderlich
2026-09-17 13:00 ` Andy Shevchenko
2026-09-17 13:20   ` Frank Wunderlich (linux)
2026-09-17 13:37     ` Andy Shevchenko [this message]
2026-09-17 13:39       ` Andy Shevchenko

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