netdev - Re: [v2][PATCH 1/1] net: phy: Add link between phy dev and mac dev

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Date:   Tue, 29 Nov 2022 12:50:46 +0100
From:   Paolo Abeni <pabeni@...hat.com>
To:     Xiaolei Wang <xiaolei.wang@...driver.com>, andrew@...n.ch,
        hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [v2][PATCH 1/1] net: phy: Add link between phy dev and mac dev

On Fri, 2022-11-25 at 12:12 +0800, Xiaolei Wang wrote:
> If the external phy used by current mac interface is
> managed by another mac interface, it means that this
> network port cannot work independently, especially
> when the system suspend and resume, the following
> trace may appear, so we should create a device link
> between phy dev and mac dev.
> 
>   WARNING: CPU: 0 PID: 24 at drivers/net/phy/phy.c:983 phy_error+0x20/0x68
>   Modules linked in:
>   CPU: 0 PID: 24 Comm: kworker/0:2 Not tainted 6.1.0-rc3-00011-g5aaef24b5c6d-dirty #34
>   Hardware name: Freescale i.MX6 SoloX (Device Tree)
>   Workqueue: events_power_efficient phy_state_machine
>   unwind_backtrace from show_stack+0x10/0x14
>   show_stack from dump_stack_lvl+0x68/0x90
>   dump_stack_lvl from __warn+0xb4/0x24c
>   __warn from warn_slowpath_fmt+0x5c/0xd8
>   warn_slowpath_fmt from phy_error+0x20/0x68
>   phy_error from phy_state_machine+0x22c/0x23c
>   phy_state_machine from process_one_work+0x288/0x744
>   process_one_work from worker_thread+0x3c/0x500
>   worker_thread from kthread+0xf0/0x114
>   kthread from ret_from_fork+0x14/0x28
>   Exception stack(0xf0951fb0 to 0xf0951ff8)
> 
> Signed-off-by: Xiaolei Wang <xiaolei.wang@...driver.com>
> ---
>  drivers/net/phy/phy_device.c | 12 ++++++++++++
>  include/linux/phy.h          |  2 ++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 57849ac0384e..ca6d12f37066 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1511,6 +1511,15 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
>  	phy_resume(phydev);
>  	phy_led_triggers_register(phydev);
>  
> +	/**
> +	 * If the external phy used by current mac interface is managed by
> +	 * another mac interface, so we should create a device link between
> +	 * phy dev and mac dev.
> +	 */
> +	if (phydev->mdio.bus->parent && dev->dev.parent != phydev->mdio.bus->parent)
> +		phydev->devlink = device_link_add(dev->dev.parent, &phydev->mdio.dev,
> +						  DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
> +
>  	return err;
>  
>  error:
> @@ -1748,6 +1757,9 @@ void phy_detach(struct phy_device *phydev)
>  	struct module *ndev_owner = NULL;
>  	struct mii_bus *bus;
>  
> +	if (phydev->devlink)
> +		device_link_del(phydev->devlink);
> +
>  	if (phydev->sysfs_links) {
>  		if (dev)
>  			sysfs_remove_link(&dev->dev.kobj, "phydev");
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index ddf66198f751..f7f8b909fed0 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -617,6 +617,8 @@ struct phy_device {
>  	/* And management functions */
>  	struct phy_driver *drv;
>  
> +	struct device_link *devlink;

Sorry for the late nit picking, but could you please add the kdoc
documentation for this new field?

Also, please specify explicitly the net-next target tree on repost, as
per Florian's request.

Thanks,

Paolo