linux-kernel - Re: [RFT PATCH 1/2] net: dsa: mv88e6xxx: Add EEE support

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Message-ID: <54EBE221.2000703@roeck-us.net>
Date:	Mon, 23 Feb 2015 18:29:53 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org, andrew@...n.ch, f.fainelli@...il.com,
	linux-kernel@...r.kernel.org
Subject: Re: [RFT PATCH 1/2] net: dsa: mv88e6xxx: Add EEE support

On 02/23/2015 02:19 PM, David Miller wrote:
> From: Guenter Roeck <linux@...ck-us.net>
> Date: Mon, 23 Feb 2015 08:26:09 -0800
>
>> +	/* Don't call phy_init_eee for now. It fails if the link is down,
>> +	 * but that should not really be a reason to fail configuration.
>> +	 */
>
> I think there is some confusion about phy_init_eee().
>
> You invoke it after a link has been established.  Because programming
> the MDIO registers that turn on EEE can only be done if the link
> is configured in a certain way.
>
> If you look at stmmac, it invokes phy_init_eee() via it's adjust_link
> callback passed to phy_connect().  This is basically how I would
> expect it to be used, in that any time a link parameter changes we
> rerun phy_init_eee() to check the link partner registers, duplex
> state, etc.
>
> SXGBE on the other hand seems to not be using phy_init_eee() properly,
> it only invokes it once per device open and that makes no sense at all
> because then you're stuck with the eee state resulting from the link
> state at open time.
>
That explains a lot. I suspect the use in bcm_sf2 and bcmgenet is also
not as intended.

Thanks,
Guenter

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