Atheros 5424/2424 device periodically gets into state with 'no carrier' or 'device timeout'

[Yuri]

I have a laptop with this device which periodically spontaneously loses 
connection, gets into 'no carrier' state.
'/etc/rc.d/netif restart' doesn't help. I believe it brings it down and 
up too fast.
'/etc/rc.d/netif stop && sleep 3 && /etc/rc.d/netif start' usually 
helps. But this command sometimes also leaves it into 'no career' state.
I also saw the situation when after the hot reboot ath0 came up with 
messages 'device timeout', and was never usable.

Yuri


9.2-STABLE
ath0: <Atheros 5424/2424> mem 0x8b100000-0x8b10ffff irq 18 at device 0.0 
on pci4
ath0: AR2425 mac 14.2 RF5424 phy 7.0