Hi Marek,
On 7/21/21 10:07 PM, Marek Behún wrote:
On Wed, 21 Jul 2021 21:50:07 +0200
Andrew Lunn <andrew@xxxxxxx> wrote:
Hi Heiner,
in sysfs, all devices registered under LED class will have symlinks in
/sys/class/leds. This is how device classes work in Linux.
There is a standardized format for LED device names, please look at
Documentation/leds/leds-class.rst.
Basically the LED name is of the format
devicename:color:function
The interesting part here is, what does devicename mean, in this
context?
We cannot use the interface name, because it is not unique, and user
space can change it whenever it wants. So we probably need to build
something around the bus ID, e.g. pci_id. Which is not very friendly
:-(
Unfortunately there isn't consensus about what the devicename should
mean. There are two "schools of thought":
1. device name of the trigger source for the LED, i.e. if the LED
blinks on activity on mmc0, the devicename should be mmc0. We have
talked about this in the discussions about ethernet PHYs.
In the case of the igc driver if the LEDs are controlled by the MAC,
I guess some PCI identifier would be OK. Or maybe ethernet-mac
identifier, if we have something like that? (Since we can't use
interface names due to the possibility of renaming.)
Pavel and I are supporters of this scheme.
2. device name of the LED controller. For example LEDs controlled by
the maxim,max77650-led controller (leds-max77650.c) define device
name as "max77650"
Jacek supports this scheme.
I believe you must have misinterpreted some my of my statements.
The whole effort behind LED naming unification was getting rid of
hardware device names in favour of Linux provided device names.
See e.g. the excerpt from Documentation/leds/leds-class.rst:
- devicename:
it should refer to a unique identifier created by the kernel,
like e.g. phyN for network devices or inputN for input devices,
rather
than to the hardware; the information related to the product
and the bus
to which given device is hooked is available in sysfs and can be
retrieved using get_led_device_info.sh script from tools/leds;
generally
this section is expected mostly for LEDs that are somehow
associated with
other devices.
--
Best regards,
Jacek Anaszewski
