netdev - Re: [PATCH RFCv2 3/6] net: phy: provide phy_resume/phy

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Date:	Thu, 5 Dec 2013 16:08:44 -0800
From:	Florian Fainelli <f.fainelli@...il.com>
To:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Cc:	David Miller <davem@...emloft.net>,
	Mugunthan V N <mugunthanvnm@...com>,
	netdev <netdev@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFCv2 3/6] net: phy: provide phy_resume/phy_suspend helpers

2013/12/4 Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>:
> This adds helper functions to resume and suspend a given phy_device
> by calling the corresponding driver callbacks if available.
>
> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
> ---
> Changelog:
> RFCv1->RFCv2:
> - only suspend if WOL is not enabled
> - remove EXPORT_SYMBOL for phy_suspend/resume
>
> Cc: David Miller <davem@...emloft.net>
> Cc: Florian Fainelli <f.fainelli@...il.com>
> Cc: Mugunthan V N <mugunthanvnm@...com>
> Cc: netdev@...r.kernel.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/net/phy/phy_device.c |   24 ++++++++++++++++++++++++
>  include/linux/phy.h          |    2 ++
>  2 files changed, 26 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index d6447b3..6f0e9e4 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -625,6 +625,30 @@ void phy_detach(struct phy_device *phydev)
>  }
>  EXPORT_SYMBOL(phy_detach);
>
> +int phy_suspend(struct phy_device *phydev)
> +{
> +       struct phy_driver *phydrv = to_phy_driver(phydev->dev.driver);
> +       struct ethtool_wolinfo wol;
> +
> +       /* If the device has WOL enabled, we cannot suspend the PHY */
> +       wol.cmd = ETHTOOL_GWOL;
> +       phy_ethtool_get_wol(phydev, &wol);
> +       if (wol.wolopts)
> +               return -EBUSY;

I wonder if we should not set a flag in the phy device structure which
says "someone called my phydrv->set_wol() callback, this succeeded and
WoL is now enabled for me", rather than using this potentially racy
call? This would have to be modified in phy_ethtool_set_wol() for
instance?

This is kind of theoretical though as I can't picture a case where
this sequence of events would happen in real-life.
--
Florian
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