netdev - Re: [PATCH net] net: phy: aquantia: wait for the suspend/resume operations to finish

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Date:   Mon, 5 Sep 2022 17:00:27 +0000
From:   Ioana Ciornei <ioana.ciornei@....com>
To:     "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "andrew@...n.ch" <andrew@...n.ch>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>
Subject: Re: [PATCH net] net: phy: aquantia: wait for the suspend/resume
 operations to finish

On Mon, Sep 05, 2022 at 04:58:33PM +0300, Ioana Ciornei wrote:
> The Aquantia datasheet notes that after issuing a Processor-Intensive
> MDIO operation, like changing the low-power state of the device, the
> driver should wait for the operation to finish before issuing a new MDIO
> command.
> 
> The new aqr107_wait_processor_intensive_op() function is added which can
> be used after these kind of MDIO operations. At the moment, we are only
> adding it at the end of the suspend/resume calls.
> 
> The issue was identified on a board featuring the AQR113C PHY, on
> which commands like 'ip link (..) up / down' issued without any delays
> between them would render the link on the PHY to remain down.
> The issue was easy to reproduce with a one-liner:
>  $ ip link set dev ethX down; ip link set dev ethX up; \
>  ip link set dev ethX down; ip link set dev ethX up;
> 
> Fixes: ac9e81c230eb ("net: phy: aquantia: add suspend / resume callbacks for AQR107 family")
> Signed-off-by: Ioana Ciornei <ioana.ciornei@....com>

I just stumbled upon the phy_read_mmd_poll_timeout() API which takes
care of polling on an MDIO register without having to declare a separate
read function.

I'll send a v2 on this with the change later today or tomorrow.

Ioana