Re: [dpdk-dev] [PATCH v2] ixgbe: fix link down issue on x550em_x

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Feb 25, 2016 at 01:32:33AM +0000, Lu, Wenzhuo wrote:
> Hi Bruce,
> 
> > -----Original Message-----
> > From: Richardson, Bruce
> > Sent: Wednesday, February 24, 2016 10:26 PM
> > To: He, Shaopeng
> > Cc: Lu, Wenzhuo; dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v2] ixgbe: fix link down issue on x550em_x
> > 
> > On Thu, Feb 04, 2016 at 06:21:04AM +0000, He, Shaopeng wrote:
> > >
> > > > -----Original Message-----
> > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Wenzhuo Lu
> > > > Sent: Monday, February 01, 2016 4:43 PM
> > > > To: dev@dpdk.org
> > > > Subject: [dpdk-dev] [PATCH v2] ixgbe: fix link down issue on
> > > > x550em_x
> > > >
> > > > Normally the auto-negotiation is supported by FW. But on
> > > > X550EM_X_10G_T it's not supported by FW. As the port of
> > > > X550EM_X_10G_T is 10G. If we connect the port with a peer which is
> > > > 1G. The link is always down.
> > > > We have to supprted auto-neg by SW to avoid such link down issue.
> > > >
> > > > Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
> > > Acked-by: Shaopeng He <shaopeng.he@intel.com>
> > >
> > I'm a bit confused regarding the commit message and the code in the patch.
> > The commit message talks about enabling speed auto-negotiation, while the
> > code never refers to any such thing. Instead all we have are settings for
> > manipulating interrupt masks to enable PHY interrupts. I think some additional
> > information is needed to connect A and B together here.
> The reason is that the handler of the link speed auto-neg is already in the base code. It's ixgbe_handle_lasi.
> What we need is a trigger. When the advertised link speed changes, a PHY interruption will be triggered. So, we should handle this interruption and call ixgbe_handle_lasi to set the link speed correct.
> Let me add more explanation in the commit log.
> 
Yes, please do. What you have just explained makes much more sense and should
be included in the log.

> > 
> > A second, more minor nit is that the commit title never refers to link auto-
> > negotiation, but refers to this as a bug fix - which is also correct. If this is
> > primarily a bug fix, please include a fixes line if possible, but please also refer to
> > auto-neg in the title if possible too.
> I didn't add a fixes line because it doesn't fix an issue introduced by SW, or even FW, HW. As said in commit log, we hit a link down issue, but the root cause is the link speed auto-neg is not supported on this specific NIC.
> On the other NICs, link speed auto-neg is supported by FW, SW need no do anything. So we didn't implement the link speed auto-neg. But we have to implement this feature on this NIC for FW doesn't implement it.
> Should I change the tittle to "support link speed auto-neg on x550em_x"?
> 

Yes, that is probably better.

Thanks,
/Bruce