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

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Date:   Wed, 28 Jun 2017 08:59:52 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     Andrew Lunn <andrew@...n.ch>
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

Hi, Andrew

On 2017/6/27 21:29, Andrew Lunn wrote:
>>>> -		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. 
Do you mean after calling dev_close, the device is still not suspended?
If that is the case, is there any way I can ensure the device is 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.
Do you mean phydev->suspended has bad state?

> 
> Also, what about if WOL has been set before closing the device?
phy_suspend will return errro.

int phy_suspend(struct phy_device *phydev)
{
	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
	struct ethtool_wolinfo wol = { .cmd = ETHTOOL_GWOL };
	int ret = 0;

	/* If the device has WOL enabled, we cannot suspend the PHY */
	phy_ethtool_get_wol(phydev, &wol);
	if (wol.wolopts)
		return -EBUSY;

	if (phydev->drv && phydrv->suspend)
		ret = phydrv->suspend(phydev);

	if (ret)
		return ret;

	phydev->suspended = true;

	return ret;
}

Best Regard
Yunsheng Lin