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

[Russell King - ARM Linux admin]

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.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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