[dpdk-dev] [PATCH v2 36/46] net/liquidio: add API to set MTU

[Shijith Thotton]

On Tue, Mar 21, 2017 at 12:24:49PM +0000, Ferruh Yigit wrote:
> On 3/2/2017 11:32 AM, Shijith Thotton wrote:
> > Signed-off-by: Shijith Thotton <shijith.thotton at caviumnetworks.com>
> > Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
> > Signed-off-by: Derek Chickles <derek.chickles at caviumnetworks.com>
> > Signed-off-by: Venkat Koppula <venkat.koppula at caviumnetworks.com>
> > Signed-off-by: Srisivasubramanian S <ssrinivasan at caviumnetworks.com>
> > Signed-off-by: Mallesham Jatharakonda <mjatharakonda at oneconvergence.com>
> 
> <...>
> 
> >  
> >  static int
> > +lio_dev_change_vf_mtu(struct rte_eth_dev *eth_dev, uint16_t new_mtu)
> > +{
> > +	struct lio_device *lio_dev = LIO_DEV(eth_dev);
> > +
> > +	PMD_INIT_FUNC_TRACE();
> > +
> > +	if (!lio_dev->intf_open) {
> > +		lio_dev_err(lio_dev, "Port %d down, can't change MTU\n",
> > +			    lio_dev->port_id);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Limit the MTU to make sure the ethernet packets are between
> > +	 * ETHER_MIN_MTU bytes and PF's MTU
> > +	 */
> > +	if ((new_mtu < ETHER_MIN_MTU) ||
> > +			(new_mtu > lio_dev->linfo.link.s.mtu)) {
> > +		lio_dev_err(lio_dev, "Invalid MTU: %d\n", new_mtu);
> > +		lio_dev_err(lio_dev, "Valid range %d and %d\n",
> > +			    ETHER_MIN_MTU, lio_dev->linfo.link.s.mtu);
> > +		return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> 
> Is this really sets the MTU?
> "new_mtu" seems not used, except limit check, an lio_send_ctrl_pkt()
> required perhaps?

It won't set MTU for hardware and is possible only by PF. So
lio_send_ctrl_pkt is not required. VF MTU is limited by PF MTU and is
mentioned under limitations in driver documentation. Here we are
allowing upper layer to set MTU up to the value configured by PF.

Shijith