From: Heiner Kallweit <hkallwe...@gmail.com>
Date: Thu, 28 Feb 2019 07:39:15 +0100
> When debugging another issue I faced an interrupt storm in this
> driver (88E6390, port 9 in SGMII mode), consisting of alternating
> link-up / link-down interrupts. Analysis showed that the driver
> wanted to set a cmode that was set already. But so far
> mv88e6390x_port_set_cmode() doesn't check this and powers down
> SERDES, what causes the link to break, and eventually results in
> the described interrupt storm.
>
> Fix this by checking whether the cmode actually changes. We want
> that the very first call to mv88e6390x_port_set_cmode() always
> configures the registers, therefore initialize port.cmode with
> a value that is different from any supported cmode value.
> We have to take care that we only init the ports cmode once
> chip->info->num_ports is set.
>
> v2:
> - add small helper and init the number of actual ports only
>
> Fixes: 364e9d7776a3 ("net: dsa: mv88e6xxx: Power on/off SERDES on cmode
> change")
> Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com>
Applied, and queued up for -stable.
Thanks.
