Re: [PATCH net-next + leds v2 0/7] PLEASE REVIEW: Add support for LEDs on Marvell PHYs

On Wed, 9 Sep 2020 23:42:59 +0200
Andrew Lunn [off-list ref] wrote:

On Wed, Sep 09, 2020 at 06:25:45PM +0200, Marek Behún wrote:

quoted

Hello Andrew and Pavel,

please review these patches adding support for HW controlled LEDs.
The main difference from previous version is that the API is now generalized
and lives in drivers/leds, so that part needs to be reviewed (and maybe even
applied) by Pavel.

As discussed previously between you two, I made it so that the devicename
part of the LED is now in the form `ethernet-phy%i` when the LED is probed
for an ethernet PHY. Userspace utility wanting to control LEDs for a specific
network interface can access them via /sys/class/net/eth0/phydev/leds:

  mox ~ # ls /sys/class/net/eth0/phydev/leds  

It is nice they are directly in /sys/class/net/eth0/phydev. Do they
also appear in /sys/class/led?

They are in /sys/class/net/eth0/phydev/leds by default, because they
are children of the PHY device and are of `leds` class, and the PHY
subsystem creates a symlink `phydev` when PHY is attached to the
interface.
They are in /sys/class/leds/ as symlinks, because AFAIK everything in
/sys/class/<CLASS>/ is a symlink...

Have you played with network namespaces? What happens with

ip netns add ns1

ip link set eth0 netns ns1

   Andrew

If you move eth0 to other network namespace, naturally the
/sys/class/net/eth0 symlink will disappear, as will the directory it
pointed to.

The symlink phydev does will disappear from /sys/class/net/eth0/
directory after eth0 is moved to ns1, and is lost. It does not return
even if eth0 is moved back to root namespace.

The LED will of course stay in ns1 and also in root namespace, as will
the phydev the LED is a child to. But they are no longer accessible via
/sys/class/net/eth0, instead you can access the LEDs either via
/sys/class/leds or /sys/class/mdio_bus/<MDIO_BUS>/<PHY>/leds, or
without symlinks via /sys/devices/ tree.

Marek