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

Florian Fainelli florian at openwrt.org
Wed Oct 29 22:36:49 EDT 2014

Le 28/10/2014 11:46, Heiner Kallweit a écrit :
> After a little more thinking about it and looking at the code I basically have two questions:
> 1.
> 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.

Address 0 is special, since this is a MDIO broadcast address that will 
usually be handled by switches as "write to all front-panel ports".

> 2.
> 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.

I suppose that you could re-advertise auto-negotiation by calling 
genphy_config_advert() in the config_init routine.

> Rgds,
> Heiner
> 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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