linux-kernel - Re: [PATCH net-next v5 6/8] net: phy: Add phy_support

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Message-ID: <9e37a9e9-7722-407c-a2a5-b8c04b68f594@gmail.com>
Date: Thu, 22 Feb 2024 20:52:25 -0800
From: Florian Fainelli <f.fainelli@...il.com>
To: Oleksij Rempel <o.rempel@...gutronix.de>, Wei Fang <wei.fang@....com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
 Russell King <linux@...linux.org.uk>
Cc: kernel@...gutronix.de, linux-kernel@...r.kernel.org,
 netdev@...r.kernel.org, Shenwei Wang <shenwei.wang@....com>,
 Clark Wang <xiaoning.wang@....com>, NXP Linux Team <linux-imx@....com>
Subject: Re: [PATCH net-next v5 6/8] net: phy: Add phy_support_eee()
 indicating MAC support EEE

On 2/20/2024 10:21 PM, Oleksij Rempel wrote:
> From: Andrew Lunn <andrew@...n.ch>
> 
> In order for EEE to operate, both the MAC and the PHY need to support
> it, similar to how pause works. 

Kinda, a number of PHYs have added support for SmartEEE or AutoGrEEEn in 
order to provide some EEE-like power savings with non-EEE capable MACs.

Oleksij  did not you have a patch series at some point that introduced a 
smarteee field in the phy_device structure to reflect that? I thought 
that had been accepted, but maybe not.

> Copy the pause concept and add the
> call phy_support_eee() which the MAC makes after connecting the PHY to
> indicate it supports EEE. phylib will then advertise EEE when auto-neg
> is performed.
> 
> Signed-off-by: Andrew Lunn <andrew@...n.ch>
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
>   drivers/net/phy/phy_device.c | 18 ++++++++++++++++++
>   include/linux/phy.h          |  3 ++-
>   2 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 2eefee970851..269d3c7f0849 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -2910,6 +2910,24 @@ void phy_advertise_eee_all(struct phy_device *phydev)
>   }
>   EXPORT_SYMBOL_GPL(phy_advertise_eee_all);
>   
> +/**
> + * phy_support_eee - Enable support of EEE
> + * @phydev: target phy_device struct
> + *
> + * Description: Called by the MAC to indicate is supports Energy
> + * Efficient Ethernet. This should be called before phy_start() in
> + * order that EEE is negotiated when the link comes up as part of
> + * phy_start(). EEE is enabled by default when the hardware supports
> + * it.

That comment is a bit confusing without mentioning how the hardware 
default state wrt. EEE is being factored in, can we have some details here?
-- 
Florian