linux-kernel - Re: [PATCH V5 net-next 05/11] net: hibmcge: Implement some .ndo functions

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Message-ID: <853edbd1-1fca-4830-9969-e071860de2be@huawei.com>
Date: Fri, 30 Aug 2024 10:27:49 +0800
From: Jijie Shao <shaojijie@...wei.com>
To: Andrew Lunn <andrew@...n.ch>, Jakub Kicinski <kuba@...nel.org>
CC: <shaojijie@...wei.com>, <davem@...emloft.net>, <edumazet@...gle.com>,
	<pabeni@...hat.com>, <shenjian15@...wei.com>, <wangpeiyang1@...wei.com>,
	<liuyonglong@...wei.com>, <chenhao418@...wei.com>, <sudongming1@...wei.com>,
	<xujunsheng@...wei.com>, <shiyongbang@...wei.com>, <libaihan@...wei.com>,
	<jdamato@...tly.com>, <horms@...nel.org>, <jonathan.cameron@...wei.com>,
	<shameerali.kolothum.thodi@...wei.com>, <salil.mehta@...wei.com>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V5 net-next 05/11] net: hibmcge: Implement some .ndo
 functions


on 2024/8/29 22:59, Andrew Lunn wrote:
> On Thu, Aug 29, 2024 at 07:43:39AM -0700, Jakub Kicinski wrote:
>> On Thu, 29 Aug 2024 10:40:07 +0800 Jijie Shao wrote:
>>> on 2024/8/29 9:39, Jakub Kicinski wrote:
>>>> On Tue, 27 Aug 2024 21:14:49 +0800 Jijie Shao wrote:
>>>>> +static int hbg_net_open(struct net_device *dev)
>>>>> +{
>>>>> +	struct hbg_priv *priv = netdev_priv(dev);
>>>>> +
>>>>> +	if (test_and_set_bit(HBG_NIC_STATE_OPEN, &priv->state))
>>>>> +		return 0;
>>>>> +
>>>>> +	netif_carrier_off(dev);
>>>> Why clear the carrier during open? You should probably clear it once on
>>>> the probe path and then on stop.
>>> In net_open(), the GMAC is not ready to receive or transmit packets.
>>> Therefore, netif_carrier_off() is called.
>>>
>>> Packets can be received or transmitted only after the PHY is linked.
>>> Therefore, netif_carrier_on() should be called in adjust_link.
>> But why are you calling _off() during .ndo_open() ?
>> Surely the link is also off before ndo_open is called?
> I wounder what driver they copied?
>
> The general trend is .probe() calls netif_carrier_off(). After than,
> phylib/phylink is in control of the carrier and the MAC driver does
> not touch it. in fact, when using phylink, if you try to change the
> carrier, you will get SHOUTED at from Russell.
>
> 	Andrew

Read the PHY driver code:
netif_carrier_on() or netif_carrier_off()
has been called in phy_link_change() based on the link status.
Therefore, the driver does not need to process it.

static void phy_link_change(struct phy_device *phydev, bool up)
{
	struct net_device *netdev = phydev->attached_dev;

	if (up)
		netif_carrier_on(netdev);
	else
		netif_carrier_off(netdev);
	phydev->adjust_link(netdev);
	if (phydev->mii_ts && phydev->mii_ts->link_state)
		phydev->mii_ts->link_state(phydev->mii_ts, phydev);
}

Thank you. I'll delete it in v6.
	Jijie Shao