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

From: Paolo Abeni
Date: Tue Nov 29 2022 - 06:52:01 EST


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@xxxxxxxxxxxxx>
> ---
> 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