Re: [PATCH net-next RFC V1 3/5] net: Introduce field for the MII time stamper.

Florian Fainelli
2018-03-21T19:12:13Z

On 03/21/2018 11:58 AM, Richard Cochran wrote:
> This patch adds a new field to the network device structure to reference
> a time stamping device on the MII bus. By decoupling the time stamping
> function from the PHY device, we pave the way to allowing a non-PHY
> device to take this role.
>
> Signed-off-by: Richard Cochran <richardcochran@gmail.com>
> ---
> drivers/net/phy/mdio_bus.c | 51 +++++++++++++++++++++++++++++++++++++++++++++-
> include/linux/netdevice.h | 1 +
> 2 files changed, 51 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 24b5511222c8..fdac8c8ac272 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -717,6 +717,47 @@ static int mdio_uevent(struct device *dev, struct kobj_uevent_env *env)
> return 0;
> }
>
> +static bool mdiodev_supports_timestamping(struct mdio_device *mdiodev)
> +{
> + if (mdiodev->ts_info && mdiodev->hwtstamp &&
> + mdiodev->rxtstamp && mdiodev->txtstamp)
> + return true;
> + else
> + return false;
> +}
> +
> +static int mdiobus_netdev_notification(struct notifier_block *nb,
> + unsigned long msg, void *ptr)
> +{
> + struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
> + struct phy_device *phydev = netdev->phydev;
> + struct mdio_device *mdev;
> + struct mii_bus *bus;
> + int i;
> +
> + if (netdev->mdiots || msg != NETDEV_UP || !phydev)
> + return NOTIFY_DONE;

You are still assuming that we have a phy_device somehow, whereas you
parch series wants to solve that for generic MDIO devices, that is a bit
confusing.

> +
> + /*
> + * Examine the MII bus associated with the PHY that is
> + * attached to the MAC. If there is a time stamping device
> + * on the bus, then connect it to the network device.
> + */
> + bus = phydev->mdio.bus;
> +
> + for (i = 0; i < PHY_MAX_ADDR; i++) {
> + mdev = bus->mdio_map[i];
> + if (!mdev)
> + continue;
> + if (mdiodev_supports_timestamping(mdev)) {
> + netdev->mdiots = mdev;
> + return NOTIFY_OK;

What guarantees that netdev->mdiots gets cleared? Also, why is this done
with a notifier instead of through phy_{connect,attach,disconnect}? It
looks like we still have this requirement of the mdio TS device being a
phy_device somehow, I am confused here...

> + }
> + }
> +
> + return NOTIFY_DONE;
> +}
> +
> #ifdef CONFIG_PM
> static int mdio_bus_suspend(struct device *dev)
> {

> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 5fbb9f1da7fd..223d691aa0b0 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1943,6 +1943,7 @@ struct net_device {
> struct netprio_map __rcu *priomap;
> #endif
> struct phy_device *phydev;
> + struct mdio_device *mdiots;

phy_device embedds a mdio_device, can you find a way to rework the PHY
PTP code to utilize the phy_device's mdio instance so do not introduce
yet another pointer in that big structure that net_device already is?

> struct lock_class_key *qdisc_tx_busylock;
> struct lock_class_key *qdisc_running_key;
> bool proto_down;
>

--
Florian