Re: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support device reset

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

On Mon, Jun 20, 2016 at 09:17:14AM -0700, Stephen Hemminger wrote:
> On Mon, 20 Jun 2016 14:44:11 +0530
> Jerin Jacob <jerin.jacob@caviumnetworks.com> wrote:
> 
> > On Mon, Jun 20, 2016 at 02:24:27PM +0800, Wenzhuo Lu wrote:
> > > Add an API to reset the device.
> > > It's for VF device in this scenario, kernel PF + DPDK VF.
> > > When the PF port down->up, APP should call this API to
> > > reset VF port. Most likely, APP should call it in its
> > > management thread and guarantee the thread safe. It means
> > > APP should stop the rx/tx and the device, then reset the
> > > device, then recover the device and rx/tx.
> > 
> > Following is _a_ use-case for Device reset. But may be not be _the_ use
> > case. IMO, We need to first say expected behavior of this API and add a use-case
> > later.
> > 
> > Other use-case would be, PCIe VF with functional level reset for SRIOV
> > migration.
> > Are we on same page?
> 
> 
> In my experience with Linux devices, this is normally handled by the
> device driver in the start routine.  Since any use case which needs
> this is going to do a stop/reset/start sequence, why not just have
> the VF device driver do this in the start routine?.
> 
> Adding yet another API and state transistion if not necessary increases
> the complexity and required test cases for all devices.

I agree with Stephen here.I think if application needs to call start
after the device reset then we could add this logic in start itself
rather exposing a yet another API

>