From: "Marek Behún" <kabel@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Lunn <andrew@lunn.ch>, Pavel Machek <pavel@ucw.cz>,
"linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>,
netdev@vger.kernel.org,
Jacek Anaszewski <jacek.anaszewski@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: are device names part of sysfs ABI? (was Re: devicename part of LEDs under ethernet MAC / PHY)
Date: Mon, 4 Oct 2021 09:04:38 +0200 [thread overview]
Message-ID: <20211004090438.588a8a89@thinkpad> (raw)
In-Reply-To: <YVqhMeuDI0IZL/zY@kroah.com>
Hi Greg,
On Mon, 4 Oct 2021 08:37:37 +0200
Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> On Sun, Oct 03, 2021 at 10:53:38PM +0200, Marek Behún wrote:
> > Hello Greg,
> >
> > could you give your opinion on this discussion?
>
> What discussion? Top posting ruins that :(
Sorry, the discussion is here
https://lore.kernel.org/linux-leds/20211001144053.3952474a@thinkpad/T/
But the basic question is below, so you don't need to read the
discussion.
> > Are device names (as returned by dev_name() function) also part of
> > sysfs ABI? Should these names be stable across reboots / kernel
> > upgrades?
>
> Stable in what exact way?
Example:
- Board has an ethernet PHYs that is described in DT, and therefore
has stable sysfs path (derived from DT path), something like
/sys/devices/.../mdio_bus/f1072004.mdio-mii/f1072004.mdio-mii:01
- The PHY has a subnode describing a LED.
The LED subsystem has a different naming scheme (it uses DT node name
as a last resort). When everything is okay, the dev_name() of the LED
will be something like
ethphy42:green:link
- Now suppose that the PHY driver is unloaded and loaded again. The PHY
sysfs path is unchanged, but the LED will now be named
ethphy43:green:link
Is this OK?
> Numbering of devices (where a dynamic value is part of a name, like the
> "42" in "usb42"), is never guaranteed to be stable, but the non-number
> part of the name (like "usb" is in "usb42") is stable, as that is what
> you have properly documented in the Documentation/ABI/ files defining
> the bus and class devices, right?
It does make sense for removable devices like USB. What I am asking
is whether it is also OK for devices that have stable DT nodes.
Marek
next prev parent reply other threads:[~2021-10-04 7:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-01 11:30 devicename part of LEDs under ethernet MAC / PHY Marek Behún
2021-10-01 12:29 ` Andrew Lunn
2021-10-01 12:40 ` Marek Behún
2021-10-03 20:53 ` are device names part of sysfs ABI? (was Re: devicename part of LEDs under ethernet MAC / PHY) Marek Behún
2021-10-04 6:37 ` Greg Kroah-Hartman
2021-10-04 7:04 ` Marek Behún [this message]
2021-10-04 7:10 ` Greg Kroah-Hartman
2021-10-04 7:25 ` Marek Behún
2021-10-04 7:38 ` Pavel Machek
2021-10-04 8:30 ` Greg Kroah-Hartman
2021-10-04 12:14 ` Andrew Lunn
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