From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 26 Jul 2021 09:19:26 -0400 From: "Michael S. Tsirkin" Subject: Re: [PATCH v1] virtio-mmio: Specify wait needed in driver during reset Message-ID: <20210726091851-mutt-send-email-mst@kernel.org> References: <87h7gh5od5.fsf@redhat.com> <87eebl5msn.fsf@redhat.com> MIME-Version: 1.0 In-Reply-To: <87eebl5msn.fsf@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline To: Cornelia Huck Cc: Srivatsa Vaddagiri , "jasowang@redhat.com" , "virtio-dev@lists.oasis-open.org" , Trilok Soni , Pratik Patel List-ID: On Mon, Jul 26, 2021 at 01:36:56PM +0200, Cornelia Huck wrote: > On Mon, Jul 26 2021, Srivatsa Vaddagiri wrote: > > >> > +indicated by a read of \field{Status} returning 0. Such a device MUST also > >> > fail to accept > >> > +FEATURES_OK bit if driver does not negotiate VIRTIO_F_MMIO_RESET_WAIT. > >> > >> So, this basically means that an older driver that does not know the new > >> feature bit will not work with devices offering this bit, even if it did > >> poll? This seems acceptable, I just wanted to spell it out. > > > > Yes I believe that's the desired result. Device has no way to know if driver > > will poll for reset completion or not unless it accepts the feature. > > Are you suggesting we explicitly put in some text in spec to that > > effect? > > Not sure whether it is needed (do others have an opinion?), but probably > not. What about resets before FEATURES_OK? How are these handled? -- MST