Re: [PATCH RFC leds + net-next v4 0/2] Add support for LEDs on Marvell PHYs

From: Pavel Machek <pavel@ucw.cz>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "Marek Behún" <marek.behun@nic.cz>,
	netdev@vger.kernel.org, linux-leds@vger.kernel.org,
	jacek.anaszewski@gmail.com, "Dan Murphy" <dmurphy@ti.com>,
	"Ondřej Jirman" <megous@megous.com>,
	"Russell King" <linux@armlinux.org.uk>,
	"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
	"Gregory Clement" <gregory.clement@bootlin.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC leds + net-next v4 0/2] Add support for LEDs on Marvell PHYs
Date: Sun, 30 Aug 2020 00:43:51 +0200	[thread overview]
Message-ID: <20200829224351.GA29564@duo.ucw.cz> (raw)
In-Reply-To: <20200807132920.GB2028541@lunn.ch>

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Hi!

> > > And no, I don't want phydev name there.
> > 
> > Ummm. Can we get little more explanation on that? I fear that LED
> > device renaming will be tricky and phydev would work around that
> > nicely.
> 
> Hi Pavel
> 
> The phydev name is not particularly nice:
> 
> !mdio-mux!mdio@1!switch@0!mdio:00
> !mdio-mux!mdio@1!switch@0!mdio:01
> !mdio-mux!mdio@1!switch@0!mdio:02
> !mdio-mux!mdio@2!switch@0!mdio:00
> !mdio-mux!mdio@2!switch@0!mdio:01
> !mdio-mux!mdio@2!switch@0!mdio:02
> !mdio-mux!mdio@4!switch@0!mdio:00
> !mdio-mux!mdio@4!switch@0!mdio:01
> !mdio-mux!mdio@4!switch@0!mdio:02
> 400d0000.ethernet-1:00
> 400d0000.ethernet-1:01
> fixed-0:00

Not nice, I see. In particular, it contains ":"... which would be a
problem.

> The interface name are:
> 
> 1: lo:
> 2: eth0:
> 3: eth1:
> 4: lan0@eth1:
> 5: lan1@eth1:
> 6: lan2@eth1:
> 7: lan3@eth1:
> 8: lan4@eth1:
> 9: lan5@eth1:
> 10: lan6@eth1:
> 11: lan7@eth1:
> 12: lan8@eth1:
> 13: optical3@eth1:
> 14: optical4@eth1:

OTOH... renaming LEDs when interface is renamed... sounds like a
disaster, too.

> You could make a good guess at matching to two together, but it is
> error prone. Phys are low level things which the user is not really
> involved in. They interact with interface names. ethtool, ip, etc, all
> use interface names. In fact, i don't know of any tool which uses
> phydev names.

So... proposal:

Users should not be dealing with sysfs interface directly, anyway. We
should have a tool for that. It can live in kernel/tools somewhere, I
guess.

Would we name leds phy0:... (with simple incrementing number), and
expose either interface name or phydev name as a attribute?

So user could do

cat /sys/class/leds/phy14:green:foobar/netdev
lan5@eth1:

and we'd have tool hiding that complexity...

Best regards,

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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