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Tsirkin" , Jason Wang , Xuan Zhuo , linux-can@vger.kernel.org, virtualization@lists.linux.dev, Wolfgang Grandegger , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Stefano Garzarella , francesco@valla.it Subject: Re: [PATCH v10] can: virtio: Add virtio CAN driver Message-ID: References: <20260302-mighty-wondrous-seagull-75085c-mkl@pengutronix.de> <20260302-condor-of-nonconcrete-infinity-d3ddbb-mkl@pengutronix.de> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20260302-condor-of-nonconcrete-infinity-d3ddbb-mkl@pengutronix.de> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: le6GNBtlJ6zGnWmGBHjZ-kl0OwhLYlUd1xFaxy4nbW0_1772466737 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Mar 02, 2026 at 02:23:42PM +0100, Marc Kleine-Budde wrote: > On 02.03.2026 11:30:34, Marc Kleine-Budde wrote: > > > +static int virtio_can_open(struct net_device *ndev) > > > +{ > > > + virtio_can_start(ndev); > > > + > > > + netif_start_queue(ndev); > > > + > > > + return 0; > > > +} > > > > Is open_candev() missing? The CAN framework requires drivers to call > > open_candev() in their ndo_open handler. open_candev() validates that > > bittiming has been configured (returns -EINVAL if bitrate is 0), checks > > CAN FD data bitrate requirements, and manages carrier state. Without this > > call, can the device be brought up without configuring bitrate? The driver > > does call close_candev() in virtio_can_close(), showing awareness of the > > CAN lifecycle. Every other CAN driver in the kernel calls open_candev() in > > its open function. > > This is true for physical CAN devices, so let's clarify things for > virtio. > > As far as I can see, there's no interface to get/set the bit timing/bit > rate from the guest, right? > AFAIU there is not such a interface. > You can set bittiming.bitrate to CAN_BITRATE_UNKNOWN, remove the > netif_carrier handling from virtio_can_start() and use open_candev(). > Will do. Thanks! Matias