Re: [PATCH net-next 10/11] net: dsa: mv88e6xxx: remove EEE support

From: Vivien Didelot
Date: Tue Aug 01 2017 - 12:37:21 EST

Hi Andrew,

Andrew Lunn <andrew@xxxxxxx> writes:

>> >> The PHY's EEE settings are already accessed by the DSA layer through the
>> >> Marvell PHY driver and there is nothing to be done for switch's MACs.
>> >
>> > I'm confused, or missing something. Does not patch #1 mean that if the
>> > DSA driver does not have a set_eee function, we always return -ENODEV
>> > in slave.c?
>> If there is a PHY, phy_init_eee (if eee_enabled is true) and
>> phy_ethtool_set_eee is called. If there is a .set_eee op, it is
>> called. If both are absent, -ENODEV is returned.
> O.K, i don't think that is correct. EEE should only be enabled if both
> the MAC and the PHY supports it. We need some way for the MAC to
> indicate it does not support EEE.
> If set_eee is optional the meaning of a NULL pointer is that the MAC
> does support EEE. So for mv88e6060, lan9303, microchip and mt7530
> which currently don't support EEE, you need to add a set_eee which
> returns -ENODEV.
> Having to implement the op to say you don't implement the feature just
> seems wrong.

Agreed, above I simply described how this patchset currently behaves.

I suggested in the previous mail to define a DSA noop so that the driver
can indicate that its MACs supports EEE, even though there's nothing to
do (and the DSA layer can learn about that):

static inline int dsa_set_mac_eee_noop(struct dsa_switch *ds,
int port,
struct ethtool_eee *e)
dev_dbg(ds->dev, "nothing to do for port %d's MAC\n", port);
return 0;

(and the respective dsa_get_mac_eee_noop() for sure.)

Second option is: we keep it KISS and let the driver define its noop,
but as I explain, it is confusion, especially for the get operation.