[dpdk-dev] i40e: pci probe fails when using one bogus sfp

Wu, Jingjing jingjing.wu at intel.com
Tue Jun 13 16:14:43 CEST 2017



> -----Original Message-----
> From: Olivier MATZ [mailto:olivier.matz at 6wind.com]
> Sent: Tuesday, June 13, 2017 4:28 PM
> To: Wu, Jingjing <jingjing.wu at intel.com>
> Cc: Xing, Beilei <beilei.xing at intel.com>; Richardson, Bruce <bruce.richardson at intel.com>;
> Zhang, Helin <helin.zhang at intel.com>; dev at dpdk.org
> Subject: Re: [dpdk-dev] i40e: pci probe fails when using one bogus sfp
> 
> Hi Jingjing,
> 
> On Mon, 12 Jun 2017 16:23:47 +0000, "Wu, Jingjing" <jingjing.wu at intel.com> wrote:
> > HI, Olivier
> >
> > > Thank you for your quick answer.
> > >
> > > Yes, the pci probing continues for the other ports even if one port
> > > failed (since v17.05, commit 10f6c93cea).
> > >
> > > But I find a bit strange to have this check about the SFP in the
> > > PCI probing function instead of having it the port initialization
> > > function. My understanding is the SFP check is not related to PCI
> > > probing. Is it consistent with other drivers?
> > >
> > Could your customer help to check what is the exactly error code is by
> > Checking the "hw->aq.asq_last_status" when eth_i40e_dev_init() fails.
> 
> I'm afraid it won't be possible, since it's a random issue that is
> not reproducible.
> 
> What do you think about adding a log in i40e_dev_sync_phy_type() to
> display the status value in case of failure? It would help for next
> times. I can submit a patch for that if you want.
>
Yes, It makes sense. Thanks for doing that.

> > Yes, it seems better PHY init fails doesn't block PCI probe. Just compared with i40e
> > Kernel version, PHY init fails doesn't block CPI probe. And there is watchdog task to
> > Check the PHY status. But DPDK is polling mode, If PCI probe fails, PCI probe continues,
> > then application need poll PHY status to support SFP change.
> 
> From what I understand, i40e_dev_sync_phy_type() was added
> to know the PHY capabilities, which useful for instance for devinfo().
> Indeed, devinfo() can be call before the port is started, so
> we need to have get the PHY capabilities before starting the port.
> 
> I've done a quick patch that:
> - keeps the call to i40e_dev_sync_phy_type() in pci probing but
>   continue in case of failure
> - add another call to i40e_dev_sync_phy_type() in port start
>   function
>
I think this workaround would not introduce issue if SFP is ready on NIC before Probe.
But I'm not sure if it can resolve the issue, because during probe, dozens of initialization work
Is ongoing. I think we need to verify it PHY init during start phase works or not. Maybe we
Need to do more than that? Not sure.

> I think it would solve the issue without impacting the result
> of the devinfo() function. What would you think of a patch like
> this?
> 
> > And I also checked ixgbe driver, it seems phy init is done at probe time.
> > In my opinion, dev_start and dev_stop is meaning ready for receiving and transmitting
> > packets, it may not be suitable to put it in the start/stop phase.
> 
> I'm wondering: what would/should occur if the SFP is unplugged and
> replugged while the port is running?
> 
> I suppose we don't have any PCI notification when unplugging/plugging
> the SFP, so I'm not sure we should have this check at the PCI level,
> because the application does not know if the bus has to be probed again.
>
We can consider about unplugging/plugging as link event in DPDK. Now we
have LSC or user can polling link status. Maybe that is a way to go.

Thanks
Jingjing


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