[RFC v4 net-next 1/4] net: phy: add MediaTek PHY driver

[DENG Qingfang]

On Tue, Apr 13, 2021 at 02:12:59PM +0100, Russell King - ARM Linux admin wrote:
> On Tue, Apr 13, 2021 at 11:59:20AM +0800, DENG Qingfang wrote:
> > Within 12 hours, I got some spontaneous link down/ups when EEE is enabled:
> > 
> > [16334.236233] mt7530 mdio-bus:1f wan: Link is Down
> > [16334.241340] br-lan: port 3(wan) entered disabled state
> > [16337.355988] mt7530 mdio-bus:1f wan: Link is Up - 1Gbps/Full - flow control rx/tx
> > [16337.363468] br-lan: port 3(wan) entered blocking state
> > [16337.368638] br-lan: port 3(wan) entered forwarding state
> > 
> > The cable is a 30m Cat.6 and never has such issue when EEE is disabled.
> > Perhaps WAKEUP_TIME_1000/100 or some PHY registers need to be fine-tuned,
> > but for now I think it should be disabled by default.
> 
> Experience with Atheros AR8035 which has a very similar issue would
> suggest that before resorting to the blunt hammer of disabling
> SmartEEE, one should definitely experiment with the 1G Tw settings.
> 
> Using 24us for 1G speeds on AR8035 helps a great deal, whereas the PHY
> defaults to 17us for 1G and 23us for 100M.

I set the 1G Tw to maximum 255us and still got the link issue..