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Date:   Tue, 10 Oct 2023 10:31:50 +0200
From:   =?UTF-8?B?S8O2cnk=?= Maincent <kory.maincent@bootlin.com>
To:     Florian Fainelli <florian.fainelli@broadcom.com>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org,
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        Jacob Keller <jacob.e.keller@intel.com>,
        Maxime Chevallier <maxime.chevallier@bootlin.com>
Subject: Re: [PATCH net-next v5 15/16] net ethtool: net: Let the active time
 stamping layer be selectable
Message-ID: <20231010103150.4f4bc187@kmaincent-XPS-13-7390>
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        <20231009155138.86458-16-kory.maincent@bootlin.com>
        <ac520b3b-bf70-4643-a259-83e91dd330a6@broadcom.com>
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On Mon, 9 Oct 2023 14:28:38 -0700
Florian Fainelli <florian.fainelli@broadcom.com> wrote:

> > +static int ethnl_set_ts_validate(struct ethnl_req_info *req_info,
> > +				 struct genl_info *info)
> > +{
> > +	struct nlattr **tb = info->attrs;
> > +	const struct net_device_ops *ops = req_info->dev->netdev_ops;
> > +
> > +	if (!tb[ETHTOOL_A_TS_LAYER])
> > +		return 0;
> > +
> > +	if (!ops->ndo_hwtstamp_set)
> > +		return -EOPNOTSUPP;  
> 
> I would check for this first, in all likelihood this is what most 
> drivers currently do not support, no need to event de-reference the 
> array of attributes.

Indeed seems more logical.

> > +static int ethnl_set_ts(struct ethnl_req_info *req_info, struct genl_info
> > *info) +{
> > +	struct net_device *dev = req_info->dev;
> > +	const struct ethtool_ops *ops = dev->ethtool_ops;
> > +	struct kernel_hwtstamp_config config = {0};
> > +	struct nlattr **tb = info->attrs;
> > +	bool mod = false;
> > +	u32 ts_layer;
> > +	int ret;
> > +
> > +	ts_layer = dev->ts_layer;

> > +
> > +	if (ts_layer & NETDEV_TIMESTAMPING && !ops->get_ts_info) {
> > +		NL_SET_ERR_MSG_ATTR(info->extack, tb[ETHTOOL_A_TS_LAYER],
> > +				    "this device cannot support
> > timestamping");  
> 
> Maybe expand the extended ack with "this devices does not support 
> MAC-based timestamping"

Ok.

> > +	/* Disable time stamping in the current layer. */
> > +	if (netif_device_present(dev) &&
> > +	    dev->ts_layer & (PHYLIB_TIMESTAMPING | NETDEV_TIMESTAMPING)) {
> > +		ret = dev_set_hwtstamp_phylib(dev, &config, info->extack);
> >  
> 
> Can we still land in this function even if no changes to the 
> timestamping configuration has been made? 

We land in this function every time we change the timestamp from a valid
one.  

> If so, would suggest first 
> getting the current configuration and compare it with the user-supplied 
> configuration if there are no changes, return.

It is already done at the beginning of the function:
> > +	ethnl_update_u32(&ts_layer, tb[ETHTOOL_A_TS_LAYER], &mod);
> > +
> > +	if (!mod)
> > +		return 0;