On Tue, Feb 27, 2024 at 10:39:41AM +0100, Bastien Curutchet wrote:

Collisions on link does not fit into one of the existing netdev triggers.

Add TRIGGER_NETDEV_COLLISION in the enum led_trigger_netdev_modes.
Add its definition in Documentation.
Add its handling in ledtrig-netdev, it can only be supported by hardware
so no software fallback is implemented.

How useful is collision? How did you test this? How did you cause
collisions to see if the LED actually worked?

As far as i can see, this is just a normal 100Base-T PHY. Everybody
uses that point-to-point nowadays. If it was an 100Base-T1, with a
shared medium, good old CSMA/CD then collision might actually be
useful.

I also disagree with not having software fallback:

ip -s link show eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 80:ee:73:83:60:27 brd ff:ff:ff:ff:ff:ff
    RX:     bytes    packets errors dropped  missed   mcast           
    4382213540983 2947876747      0       0       0  154890 
    TX:     bytes    packets errors dropped carrier collsns           
      18742773651  197507119      0       0       0       0

collsns = 0. The information is there in a standard format. However,
when did you last see it not 0?

	Andrew