netdev - Re: [PATCH NET V5 2/2] net: hns: Use phy

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Message-ID: <20170627132958.GA9921@lunn.ch>
Date:   Tue, 27 Jun 2017 15:29:58 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Yunsheng Lin <linyunsheng@...wei.com>
Cc:     davem@...emloft.net, f.fainelli@...il.com,
        huangdaode@...ilicon.com, xuwei5@...ilicon.com,
        liguozhu@...ilicon.com, Yisen.Zhuang@...wei.com,
        gabriele.paoloni@...wei.com, john.garry@...wei.com,
        linuxarm@...wei.com, salil.mehta@...wei.com, lipeng321@...wei.com,
        tremyfr@...il.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH NET V5 2/2] net: hns: Use phy_driver to setup Phy loopback

> >> -		phy_write(phy_dev, COPPER_CONTROL_REG, val);
> >> +		err = phy_resume(phy_dev);
> > 
> > Maybe this was discussed with an earlier version of these patches. Why
> > are using phy_resume() and phy_suspend()?
> When self_test is invoked with ETH_TEST_FL_OFFLINE option, hns mac driver
> call dev_close to set net dev to offline state if net dev is online.
> Doing the actual phy loolback test require phy is power up, So phy_resume
> and phy_suspend are used.

O.K, so you at least need some comments, because this is not obvious.

>From your description, it sounds like you can call phy_resume() on a
device which is not suspended. In general, suspend is expected to
store away state which will be lost when powering down a
device. Resume writes that state back into the device after it is
powered up. So resuming a device which was never suspended could write
bad state into it.

Also, what about if WOL has been set before closing the device?

      Andrew