Re: lan78xx and phy_state_machine

From: Stefan Wahren <wahrenst@gmx.net>
To: Heiner Kallweit <hkallweit1@gmail.com>,
	Russell King - ARM Linux admin <linux@armlinux.org.uk>,
	Woojung Huh <woojung.huh@microchip.com>,
	Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>
Cc: Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Daniel Wagner <dwagner@suse.de>,
	netdev@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com,
	linux-arm-kernel@lists.infradead.org,
	linux-rpi-kernel@lists.infradead.org
Subject: Re: lan78xx and phy_state_machine
Date: Wed, 16 Oct 2019 07:48:00 +0200	[thread overview]
Message-ID: <4b160706-97a4-1fd8-9ddb-00a81d0cd6bb@gmx.net> (raw)
In-Reply-To: <524267e6-df8e-d884-aeef-1ed8700e4e58@gmail.com>

Am 15.10.19 um 21:38 schrieb Heiner Kallweit:
> On 15.10.2019 00:12, Russell King - ARM Linux admin wrote:
>> On Mon, Oct 14, 2019 at 10:20:15PM +0200, Heiner Kallweit wrote:
>>> On 14.10.2019 21:51, Stefan Wahren wrote:
>>>> [add more recipients]
>>>>
>>>> Am 14.10.19 um 21:25 schrieb Daniel Wagner:
>>>>> Moving the phy_prepare_link() up in phy_connect_direct() ensures that
>>>>> phydev->adjust_link is set when the phy_check_link_status() is called.
>>>>>
>>>>> diff --git a/drivers/net/phy/phy_device.c
>>>>> b/drivers/net/phy/phy_device.c index 9d2bbb13293e..2a61812bcb0d 100644
>>>>> --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c
>>>>> @@ -951,11 +951,12 @@ int phy_connect_direct(struct net_device *dev,
>>>>> struct phy_device *phydev, if (!dev) return -EINVAL;
>>>>>
>>>>> +       phy_prepare_link(phydev, handler);
>>>>> +
>>>>>         rc = phy_attach_direct(dev, phydev, phydev->dev_flags, interface);
>>>>>         if (rc)
>>> If phy_attach_direct() fails we may have to reset phydev->adjust_link to NULL,
>>> as we do in phy_disconnect(). Apart from that change looks good to me.
>> Sorry, but it doesn't look good to me.
>>
>> I think there's a deeper question here - why is the phy state machine
>> trying to call the link change function during attach?
> After your comment I had a closer look at the lm78xx driver and few things
> look suspicious:
>
> - lan78xx_phy_init() (incl. the call to phy_connect_direct()) is called
>   after register_netdev(). This may cause races.
>
> - The following is wrong, irq = 0 doesn't mean polling.
>   PHY_POLL is defined as -1. Also in case of irq = 0 phy_interrupt_is_valid()
>   returns true.
>
> 	/* if phyirq is not set, use polling mode in phylib */
> 	if (dev->domain_data.phyirq > 0)
> 		phydev->irq = dev->domain_data.phyirq;
> 	else
> 		phydev->irq = 0;
>
> - Manually calling genphy_config_aneg() in lan78xx_phy_init() isn't
>   needed, however this should not cause our problem.
Thanks for this review. This may help to fix at least a one of all the
other issues with lan78xx.