Re: [virtio-dev] Re: [PATCH v1] virtio-mmio: Specify wait needed in driver during reset

[Srivatsa Vaddagiri <quic_svaddagi@quicinc.com>]

* Srivatsa Vaddagiri <quic_svaddagi@quicinc.com> [2021-08-18 11:43:05]:

> * Jason Wang <jasowang@redhat.com> [2021-08-18 14:04:04]:
> 
> > > Fine let me take a stab at the next version which will have this:
> > >
> > > * Introduce a status bit for device to indicate "reset in progress". This could
> > >   be adopted by other transports also (for ex PCI).
> > 
> > I may miss something discussion but any reason that the current
> > VIRTIO_MMIO_STATUS is not sufficient?
> 
> I think Mike suggested we specify what device would return while reset is in
> progress, rather than any arbitrary non-zero value:
> 
> https://lists.oasis-open.org/archives/virtio-dev/202108/msg00070.html
> 
> > > * For v3 MMIO devices, driver, after initiating reset, should wait until
> > >   status = 0 or device indicates "failure". What the driver does when it sees
> > >   failure can be implementation defined (it can give up or try reset few more
> > >   times)
> > 
> > Yes, but let's wait a little bit to see if it is agreed by others.
> 
> Sure. 

Does anyone disagree with above approach to go with MMIO version change to
handle the reset issue? I can send the next version based on it and addressing
various comments received so far.

> Mike,
> 	Do you suggest we add this as well for v3 device?
> 
> "after writing 0 to Status and before reading any fields, the driver
> MUST read Status and wait for a read to return 0 or indicate failure"


- vatsa

-- 
Qualcomm Innovation Center, Inc. is submitting the attached "feedback" as a
non-member to the virtio-dev mailing list for consideration and inclusion.