netdev - Re: [v2, 4/4] ocelot: add VCAP IS2 rule to trap PTP Ethernet frames

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Date:   Tue, 13 Aug 2019 08:25:26 +0200
From:   "Allan W . Nielsen" <allan.nielsen@...rochip.com>
To:     Yangbo Lu <yangbo.lu@....com>
CC:     <netdev@...r.kernel.org>, "David S . Miller" <davem@...emloft.net>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        "Microchip Linux Driver Support" <UNGLinuxDriver@...rochip.com>
Subject: Re: [v2, 4/4] ocelot: add VCAP IS2 rule to trap PTP Ethernet frames

The 08/13/2019 10:52, Yangbo Lu wrote:
> All the PTP messages over Ethernet have etype 0x88f7 on them.
> Use etype as the key to trap PTP messages.
> 
> Signed-off-by: Yangbo Lu <yangbo.lu@....com>
> ---
> Changes for v2:
> 	- Added this patch.
> ---
>  drivers/net/ethernet/mscc/ocelot.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
> index 6932e61..40f4e0d 100644
> --- a/drivers/net/ethernet/mscc/ocelot.c
> +++ b/drivers/net/ethernet/mscc/ocelot.c
> @@ -1681,6 +1681,33 @@ int ocelot_probe_port(struct ocelot *ocelot, u8 port,
>  }
>  EXPORT_SYMBOL(ocelot_probe_port);
>  
> +static int ocelot_ace_add_ptp_rule(struct ocelot *ocelot)
> +{
> +	struct ocelot_ace_rule *rule;
> +
> +	rule = kzalloc(sizeof(*rule), GFP_KERNEL);
> +	if (!rule)
> +		return -ENOMEM;
> +
> +	/* Entry for PTP over Ethernet (etype 0x88f7)
> +	 * Action: trap to CPU port
> +	 */
> +	rule->ocelot = ocelot;
> +	rule->prio = 1;
> +	rule->type = OCELOT_ACE_TYPE_ETYPE;
> +	/* Available on all ingress port except CPU port */
> +	rule->ingress_port = ~BIT(ocelot->num_phys_ports);
> +	rule->dmac_mc = OCELOT_VCAP_BIT_1;
> +	rule->frame.etype.etype.value[0] = 0x88;
> +	rule->frame.etype.etype.value[1] = 0xf7;
> +	rule->frame.etype.etype.mask[0] = 0xff;
> +	rule->frame.etype.etype.mask[1] = 0xff;
> +	rule->action = OCELOT_ACL_ACTION_TRAP;
> +
> +	ocelot_ace_rule_offload_add(rule);
> +	return 0;
> +}
> +
>  int ocelot_init(struct ocelot *ocelot)
>  {
>  	u32 port;
> @@ -1708,6 +1735,7 @@ int ocelot_init(struct ocelot *ocelot)
>  	ocelot_mact_init(ocelot);
>  	ocelot_vlan_init(ocelot);
>  	ocelot_ace_init(ocelot);
> +	ocelot_ace_add_ptp_rule(ocelot);
>  
>  	for (port = 0; port < ocelot->num_phys_ports; port++) {
>  		/* Clear all counters (5 groups) */
This seems really wrong to me, and much too hard-coded...

What if I want to forward the PTP frames to be forwarded like a normal non-aware
PTP switch?

What if do not want this on all ports?

If you do not have an application behind this implementing a boundary or
transparent clock, then you are breaking PTP on the network.

/Allan