Subject: Re: [PATCH net-next v5 13/16] net: Change the API of PHY default timestamp to MAC

From: Simon Horman <[email-masked]>
Date: Tue, 10 Oct 2023 17:52:08 +0200

On Mon, Oct 09, 2023 at 05:51:35PM +0200, Köry Maincent wrote:

Hi Köry,

some minor feedback from my side.

...

> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 2ce74593d6e4..2d5a6d57acb3 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1411,6 +1411,68 @@ int phy_sfp_probe(struct phy_device *phydev,
>  }
>  EXPORT_SYMBOL(phy_sfp_probe);
>  
> +/* An allowlist for PHYs selected as default timesetamping.
> + * Its use is to keep compatibility with old PTP API which is selecting
> + * these PHYs as default timestamping.
> + * The new API is selecting the MAC as default timestamping.
> + */
> +const char * const phy_timestamping_allowlist[] = {

Should this be static?

As flagged by Sparse.

> +	"Broadcom BCM5411",
> +	"Broadcom BCM5421",
> +	"Broadcom BCM54210E",
> +	"Broadcom BCM5461",
> +	"Broadcom BCM54612E",
> +	"Broadcom BCM5464",
> +	"Broadcom BCM5481",
> +	"Broadcom BCM54810",
> +	"Broadcom BCM54811",
> +	"Broadcom BCM5482",
> +	"Broadcom BCM50610",
> +	"Broadcom BCM50610M",
> +	"Broadcom BCM57780",
> +	"Broadcom BCM5395",
> +	"Broadcom BCM53125",
> +	"Broadcom BCM53128",
> +	"Broadcom BCM89610",
> +	"NatSemi DP83640",
> +	"Microchip LAN8841 Gigabit PHY",
> +	"Microchip INDY Gigabit Quad PHY",
> +	"Microsemi GE VSC856X SyncE",
> +	"Microsemi GE VSC8575 SyncE",
> +	"Microsemi GE VSC8582 SyncE",
> +	"Microsemi GE VSC8584 SyncE",
> +	"NXP C45 TJA1103",
> +	NULL,
> +};
> +
> +/**
> + * phy_set_timestamp - set the default selected timestamping device
> + * @dev: Pointer to net_device
> + * @phydev: Pointer to phy_device
> + *
> + * This is used to set default timestamping device taking into account
> + * the new API choice, which is selecting the timestamping from MAC by
> + * default.
> + */

...

> @@ -1484,6 +1546,7 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
>  
>  	phydev->phy_link_change = phy_link_change;
>  	if (dev) {
> +		phy_set_timestamp(dev, phydev);
>  		phydev->attached_dev = dev;
>  		dev->phydev = phydev;
>  
> @@ -1794,6 +1857,7 @@ EXPORT_SYMBOL_GPL(devm_phy_package_join);
>  void phy_detach(struct phy_device *phydev)
>  {
>  	struct net_device *dev = phydev->attached_dev;
> +	const struct ethtool_ops *ops = dev->ethtool_ops;

Elsewhere in this function it is assumed that dev may be NULL.
But here it is dereferenced unconditionally.

As flagged by Smatch.

>  	struct module *ndev_owner = NULL;
>  	struct mii_bus *bus;
>  
> @@ -1812,6 +1876,10 @@ void phy_detach(struct phy_device *phydev)
>  
>  	phy_suspend(phydev);
>  	if (dev) {
> +		if (ops->get_ts_info)
> +			dev->ts_layer = NETDEV_TIMESTAMPING;
> +		else
> +			dev->ts_layer = NO_TIMESTAMPING;
>  		phydev->attached_dev->phydev = NULL;
>  		phydev->attached_dev = NULL;
>  	}

...