netdev - Re: [PATCH V3 net 2/2] net: phy: at803x: add disable hibernation mode support

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Message-ID: <Yv6TA9xfx4m2+YrH@lunn.ch>
Date:   Thu, 18 Aug 2022 21:29:07 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     wei.fang@....com
Cc:     hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        f.fainelli@...il.com, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 net 2/2] net: phy: at803x: add disable hibernation
 mode support

On Thu, Aug 18, 2022 at 11:00:54AM +0800, wei.fang@....com wrote:
> From: Wei Fang <wei.fang@....com>
> 
> When the cable is unplugged, the Atheros AR803x PHYs will enter
> hibernation mode after about 10 seconds if the hibernation mode
> is enabled and will not provide any clock to the MAC. But for
> some MACs, this feature might cause unexpected issues due to the
> logic of MACs.
> Taking SYNP MAC (stmmac) as an example, if the cable is unplugged
> and the "eth0" interface is down, the AR803x PHY will enter
> hibernation mode. Then perform the "ifconfig eth0 up" operation,
> the stmmac can't be able to complete the software reset operation
> and fail to init it's own DMA. Therefore, the "eth0" interface is
> failed to ifconfig up. Why does it cause this issue? The truth is
> that the software reset operation of the stmmac is designed to
> depend on the RX_CLK of PHY.
> So, this patch offers an option for the user to determine whether
> to disable the hibernation mode of AR803x PHYs.
> 
> Signed-off-by: Wei Fang <wei.fang@....com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew