linux-kernel - Re: [PATCH v1 1/1] leds: Unexport of_led

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Message-ID: <20251211-plural-generic-c7e78cd51f9d@thorsis.com>
Date: Thu, 11 Dec 2025 13:34:10 +0100
From: Alexander Dahl <ada@...rsis.com>
To: "andriy.shevchenko@...ux.intel.com" <andriy.shevchenko@...ux.intel.com>
Cc: Jonathan Brophy <J.Brophy@...killsystems.co.nz>,
	"lee@...nel.org" <lee@...nel.org>,
	"linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
	Pavel Machek <pavel@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/1] leds: Unexport of_led_get()

Hello Andy,

Am Wed, Dec 10, 2025 at 11:54:19PM +0200 schrieb andriy.shevchenko@...ux.intel.com:
> On Wed, Dec 10, 2025 at 06:30:06PM +0000, Jonathan Brophy wrote:
> > > Can you elaborate? I think your downstream code (I have no other ideas where you Q came from)
> > > uses some outdated approaches. Try to look at the problem from the level of the existing APIs and 
> > > frameworks. We shouldn't really have such an issue (but it might be some special use case, I admit).
> > 
> > I'm trying to create a virtual led driver but with the removal of
> > of_led_get() im struggling to find a way to make it work.
> 
> Still it's unclear to me what it means and how the code look like.
> Perhaps you need to send some patches for the discussion (maybe as
> RFC if you think they are not upstream ready).

I guess it is about the patch series Jonathan already sent?

https://lore.kernel.org/linux-leds/20251019092331.49531-1-professorjonny98@gmail.com/T/#u

Greets
Alex

> 
> > I investigated alternative approaches to avoid of_led_get() dependency, including:
> > 
> > Direct class_find_device(led_class, ...) calls - Failed because led_class is
> > not exported (static in led-class.c)
> 
> > bus_find_device_by_fwnode() - Failed because LED devices are class devices,
> > not bus devices
> 
> > Manual iteration via class_dev_iter_init() - Failed because I cannot obtain
> > the led_class pointer
> > 
> > of_led_get() appears to be the only viable solution because:
> > 
> > It's the only exported function with access to the non-exported leds_class
> > It handles GPIO LED matching quirks (parent node vs child node)
> > It provides proper reference counting via led_put()
> > 
> > Should led_class be exported, or is there a planned fwnode-based alternative
> > to of_led_get?
> 
> You can introduce it as a precursor to your driver. But OF centric variant
> gone for good, we use fwnode in a new code.
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
> 
>