Re: [PATCH] igb_uio: remove device reset in open

["Mody, Rasesh" <Rasesh.Mody@cavium.com>]

Hi Jianfeng and Ferruh,

> From: Ferruh Yigit [mailto:ferruh.yigit@intel.com]
> Sent: Thursday, October 26, 2017 5:50 PM
> 
> On 10/26/2017 2:28 AM, Tan, Jianfeng wrote:
> > Hi Rasesh,
> >
> >
> > On 10/26/2017 7:43 AM, Mody, Rasesh wrote:
> >> Hi Ferruh,
> >>
> >>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Ferruh Yigit
> >>> Sent: Friday, October 20, 2017 9:58 AM
> >>>
> >>> On 10/20/2017 9:55 AM, Ferruh Yigit wrote:
> >>>> Remove device reset during application start, the reset for
> >>>> application exit still there.
> >>>>
> >>>> Reset in open removed because of following comments:
> >>>> 1- Device reset not completed when VF driver loaded, which cause VF
> PMD
> >>>>     initialization error.
> >>>>     Adding delay can solve the issue but will increase driver load time.
> >>>>
> >>>> 2- Reset will be issues all devices unconditionally, not very efficient
> >>>>     way.
> >>>>
> >>>> Fixes: b58eedfc7dd5 ("igb_uio: issue FLR during open and release of
> >>>> device file")
> >>>> Cc: stable@dpdk.org
> >>>>
> >>>> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> >>> Hi Jingjing, Shijith, Gregory, Harish,
> >>>
> >>> Can you please test this on top of current master (which has already
> >>> Jingjin's
> >>> fix) ?
> >> The original FLR change during igb_uio open()/release() in DPDK17.08 also
> impacts BNX2X PMD and it exhibits the issues with bare metal testing.
> >>
> >> Now, we tested this change for BNX2X PMD using latest dpdk, which has
> this fix where FLR is invoked only in the release().
> 
> Good to hear this fixed the problem.

Yes, it fixed the issue caused by pci reset during application start.

> 
> >> However, we ran into an issue when trying to reload the testpmd
> application in quick succession. The pci reset, called during the igb_uio
> release() operation, is taking longer time and adapter is still doing the FLR
> when we relaunch the application. We see this behavior with bare metal
> testing.
> >
> > If we don't reset that device, it will continue working which is a
> > more serious issue IMO.
> 
> +1

I think, it would better for the individual PMDs to take care of the reset during the application exit.

> > How long does it take to reset BTW?
> 
> I was wondering same thing.

A five minutes delay was introduced for the reload of the application, however, we continue to see the issue with FLR during the pci release() operation.

Thanks!
-Rasesh

> 
> >
> > Thanks,
> > Jianfeng
> >