> -----Original Message----- > From: Yong Wang [mailto:yongwang at vmware.com] > Sent: Friday, June 17, 2016 1:40 AM > To: Olivier Matz <olivier.matz at 6wind.com>; Xing, Beilei <beilei.xing at > intel.com>; > Wu, Jingjing <jingjing.wu at intel.com> > Cc: dev at dpdk.org; Julien Meunier <julien.meunier at 6wind.com>; Thomas > Monjalon <thomas.monjalon at 6wind.com> > Subject: Re: [dpdk-dev] [PATCH v3] i40e: configure MTU > > On 5/16/16, 5:27 AM, "dev on behalf of Olivier Matz" <dev-bounces at dpdk.org > on behalf of olivier.matz at 6wind.com> wrote: > > >Hi Beilei, > > > >On 05/13/2016 10:15 AM, Beilei Xing wrote: > >> This patch enables configuring MTU for i40e. > >> Since changing MTU needs to reconfigure queue, stop port first before > >> configuring MTU. > >> > >> Signed-off-by: Beilei Xing <beilei.xing at intel.com> > >> --- > >> v3 changes: > >> Add frame size with extra I40E_VLAN_TAG_SIZE. > >> Delete i40e_dev_rx_init(pf) cause it will be called when port starts. > >> > >> v2 changes: > >> If mtu is not within the allowed range, return -EINVAL instead of -EBUSY. > >> Delete rxq reconfigure cause rxq reconfigure will be finished in > >> i40e_dev_rx_init. > >> > >> drivers/net/i40e/i40e_ethdev.c | 34 > >> ++++++++++++++++++++++++++++++++++ > >> 1 file changed, 34 insertions(+) > >> > >> [...] > >> +static int > >> +i40e_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu) { > >> + struct i40e_pf *pf = I40E_DEV_PRIVATE_TO_PF(dev->data->dev_private); > >> + struct rte_eth_dev_data *dev_data = pf->dev_data; > >> + uint32_t frame_size = mtu + ETHER_HDR_LEN > >> + + ETHER_CRC_LEN + I40E_VLAN_TAG_SIZE; > >> + int ret = 0; > >> + > >> + /* check if mtu is within the allowed range */ > >> + if ((mtu < ETHER_MIN_MTU) || (frame_size > I40E_FRAME_SIZE_MAX)) > >> + return -EINVAL; > >> + > >> + /* mtu setting is forbidden if port is start */ > >> + if (dev_data->dev_started) { > >> + PMD_DRV_LOG(ERR, > >> + "port %d must be stopped before configuration\n", > >> + dev_data->port_id); > >> + return -ENOTSUP; > >> + } > > > >I'm not convinced that ENOTSUP is the proper return value here. > >It is usually returned when a function is not implemented, which is not > >the case here: the function is implemented but is forbidden because the > >port is running. > > > >I saw that Julien commented on your v1 that the return value should be > >one of: > > - (0) if successful. > > - (-ENOTSUP) if operation is not supported. > > - (-ENODEV) if *port_id* invalid. > > - (-EINVAL) if *mtu* invalid. > > > >But I think your initial value (-EBUSY) was fine. Maybe it should be > >added in the API instead, with the following description: > > (-EBUSY) if the operation is not allowed when the port is running > > AFAICT, the same check is not done for other drivers that implement the > mac_set > op. Wouldn?t it make more sense to have the driver disable the port, > reconfigure and re-enable it in this case, instead of returning error code? > If the > consensus in DPDK is to have the application disable the port first, we need > to > enforce this policy across all devices and clearly document this behavior. > Hi, For ixgbe/igb, there's register for MTU during runtime, but for i40e, setting MTU is finished by firmware during configuration. There'll be some risk when disable the port, reconfigure and re-enable the port, so return error code in this case currently. Thanks for your comments, we'll improve the document later.
> >This would allow the application to take its dispositions to stop the > >port and restart it with the proper jumbo_frame argument. > > > >+CC Thomas which maintains ethdev API. > > > > > >Regards, > >Olivier
