Re: [PATCH RFC] leds: Add support for per-LED device triggers

From: "Ondřej Jirman" <megous@megous.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: linux-kernel@vger.kernel.org,
	Jacek Anaszewski <jacek.anaszewski@gmail.com>,
	Dan Murphy <dmurphy@ti.com>,
	"open list:LED SUBSYSTEM" <linux-leds@vger.kernel.org>,
	marek.behun@nic.cz
Subject: Re: [PATCH RFC] leds: Add support for per-LED device triggers
Date: Sun, 12 Jul 2020 15:49:11 +0200	[thread overview]
Message-ID: <20200712134911.r3lig4hgyqhmslth@core.my.home> (raw)
In-Reply-To: <20200712072554.GC4721@duo.ucw.cz>

Hello,

On Sun, Jul 12, 2020 at 09:25:54AM +0200, Pavel Machek wrote:
> On Sat 2020-07-11 23:01:11, Ondřej Jirman wrote:
> > Hello Pavel,
> > 
> > On Sat, Jul 11, 2020 at 12:04:09PM +0200, Pavel Machek wrote:
> > > Hi!
> > > 
> > > > Some LED controllers may come with an internal HW triggering mechanism
> > > > for the LED and an ability to switch between user control of the LED,
> > > > or the internal control. One such example is AXP20X PMIC, that allows
> > > > wither for user control of the LED, or for internal control based on
> > > > the state of the battery charger.
> > > > 
> > > > Add support for registering per-LED device trigger.
> > > > 
> > > > Names of private triggers need to be globally unique, but may clash
> > > > with other private triggers. This is enforced during trigger
> > > > registration. Developers can register private triggers just like
> > > > the normal triggers, by setting private_led to a classdev
> > > > of the LED the trigger is associated with.
> > > 
> > > What about this? Should address Marek's concerns about resource use...
> > 
> > What concerns? Marek's concerns seem to be about case where we register
> > a trigger for (each led * self-working configuration) which I admit
> > can be quite a lot of triggers if there are many functions. But that's
> > not my proposal.
> > 
> > My proposal is to only register on trigger per LED at most. So on my
> > system that's 1 extra trigger and on Marek's system that'd be 48 new
> > triggers. Neither seems like a meaningful problem from resource
> > use perspective.
> 
> So.. 48 triggers on Marek's systems means I'll not apply your patch.
> 
> Please take a look at my version, it is as simple and avoids that
> problem.

I would, but I don't see your version linked or mentioned in this thread.

thank you and regards,
	o.

> If it works for you, you can submit it properly and I'll likely accept
> it.
> 
> Best regards,
> 									Pavel
> -- 
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html