[OpenWrt-Devel] Autoneg problems with ar8216 on kernel 3.14 (related to ticket 17800)

Heiner Kallweit hkallweit1 at gmail.com
Tue Oct 28 14:46:00 EDT 2014

After a little more thinking about it and looking at the code I basically have two questions:

Is it actually needed to exclude certain phy's in ar8xxx_phy_config_aneg?
(At least for AR8327 it doesn't get called with an addr != 0 anyway)
Else we could remove ar8xxx_phy_config_aneg and directly register genphy_config_aneg as
callback for autoneg configuration.

Call sequence with regard to ar8216 is:
ar8216: ar8xxx_phy_probe
phy: phy_attach_direct
phy: phy_init_hw
ar8216: ar8xxx_phy_config_init
ar8216: ar8xxx_phy_config_aneg

ar8216 driver handles AR8327/AR8337 different from the other supported switch types.
ar8xxx_start incl. more detailed configuration is called from ar8xxx_phy_probe already.
For the other switch types it's called from ar8xxx_phy_config_init.

I wonder whether doing detailed configuration in the probe stage might be too early.
phy_init_hw resets the switch anyway later.
Doing the detailed setup in ar8xxx_phy_config_init seems to be more suited however
there might be good reason why it's handled the way it is.


Am 27.10.2014 um 22:00 schrieb Heiner Kallweit:
> With two different TPLINK routers (both with a AR8327N switch) I faced the issue that with
> kernel 3.14 certain switch ports used 10MBit/half only.
> Under kernel 3.10 everything was fine and the same ports used 1000MBit/full.
> As the ar8216 driver is the same I had a look at the common phy code in drivers/net/phy.
> In function phy_init_hw in phy_device.c kernel 3.14 resets the phy whilst 3.10 does not.
> The issue turned out to be that when resetting only flag BMCR_RESET is set, not BMCR_ANENABLE.
> (In ar8216.c always both flags are set when the switch is reset)
> Therefore autoneg was not enabled. Also later in the boot process it doesn't get enabled.
> Adding BMCR_ANENABLE solved the problem and now also under 3.14 all ports use 1000MBit/full.
> However I'm not sure whether it's a poper fix to add BMCR_ANENABLE in this generic phy function.
> It might not be appropriate for other phy's.
> After resetting the switch later in the boot process ar8xxx_phy_config_aneg is called with
> phydev->addr being 0.
> In this case the function returns immediately. Otherwise it would call genphy_config_aneg.
> Calling genphy_config_aneg would also solve the problem as it checks for BMCR_ANENABLE
> being set and sets it if needed.
> I don't know the reason why genphy_config_aneg isn't called in case of addr 0.
> Or is this a typo and the check actually should be addr != 0 ?
> Rgds, Heiner
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