Re: [PATCH net-next v3 2/2] net: phy: aquantia: allow forcing order of MDI pairs

[Andrew Lunn <andrew@lunn.ch>]

On Fri, Oct 04, 2024 at 05:18:16PM +0100, Daniel Golle wrote:
> Despite supporting Auto MDI-X, it looks like Aquantia only supports
> swapping pair (1,2) with pair (3,6) like it used to be for MDI-X on
> 100MBit/s networks.
> 
> When all 4 pairs are in use (for 1000MBit/s or faster) the link does not
> come up with pair order is not configured correctly, either using
> MDI_CFG pin or using the "PMA Receive Reserved Vendor Provisioning 1"
> register.
> 
> Normally, the order of MDI pairs being either ABCD or DCBA is configured
> by pulling the MDI_CFG pin.
> 
> However, some hardware designs require overriding the value configured
> by that bootstrap pin. The PHY allows doing that by setting a bit in
> "PMA Receive Reserved Vendor Provisioning 1" register which allows
> ignoring the state of the MDI_CFG pin and another bit configuring
> whether the order of MDI pairs should be normal (ABCD) or reverse
> (DCBA). Pair polarity is not affected and remains identical in both
> settings.
> 
> Introduce property "marvell,mdi-cfg-order" which allows forcing either
> normal or reverse order of the MDI pairs from DT.
> 
> If the property isn't present, the behavior is unchanged and MDI pair
> order configuration is untouched (ie. either the result of MDI_CFG pin
> pull-up/pull-down, or pair order override already configured by the
> bootloader before Linux is started).
> 
> Forcing normal pair order is required on the Adtran SDG-8733A Wi-Fi 7
> residential gateway.
> 
> Signed-off-by: Daniel Golle <daniel@makrotopia.org>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew