> -----Original Message-----
> From: Bjorn Andersson <[email protected]>
> Sent: Wednesday, February 25, 2026 9:53 AM
> To: Shenwei Wang <[email protected]>
> Cc: Andrew Lunn <[email protected]>; Mathieu Poirier
> <[email protected]>; Arnaud POULIQUEN
> <[email protected]>; Linus Walleij <[email protected]>; Bartosz
> Golaszewski <[email protected]>; Jonathan Corbet <[email protected]>; Rob Herring
> <[email protected]>; Krzysztof Kozlowski <[email protected]>; Conor Dooley
> <[email protected]>; Frank Li <[email protected]>; Sascha Hauer
> <[email protected]>; Shuah Khan <[email protected]>; linux-
> [email protected]; [email protected]; [email protected];
> Pengutronix Kernel Team <[email protected]>; Fabio Estevam
> <[email protected]>; Peng Fan <[email protected]>;
> [email protected]; [email protected];
> [email protected]; [email protected]; dl-linux-imx
> <linux-
> [email protected]>; Bartosz Golaszewski <[email protected]>
> Subject: [EXT] Re: [PATCH v8 3/4] gpio: rpmsg: add generic rpmsg GPIO driver
> On Tue, Feb 24, 2026 at 10:43:06PM +0000, Shenwei Wang wrote:
> >
> >
> > > -----Original Message-----
> > > From: Andrew Lunn <[email protected]>
> > > Sent: Tuesday, February 24, 2026 4:15 PM
> > > To: Shenwei Wang <[email protected]>
> > > Cc: Mathieu Poirier <[email protected]>; Bjorn Andersson
> > > <[email protected]>; Arnaud POULIQUEN
> > > <[email protected]>; Linus Walleij <[email protected]>;
> > > Bartosz Golaszewski <[email protected]>; Jonathan Corbet
> > > <[email protected]>; Rob Herring <[email protected]>; Krzysztof Kozlowski
> > > <[email protected]>; Conor Dooley <[email protected]>; Frank Li
> > > <[email protected]>; Sascha Hauer <[email protected]>; Shuah
> > > Khan <[email protected]>; linux- [email protected];
> > > [email protected]; [email protected]; Pengutronix
> > > Kernel Team <[email protected]>; Fabio Estevam
> > > <[email protected]>; Peng Fan <[email protected]>;
> > > [email protected]; [email protected];
> > > [email protected]; [email protected];
> > > dl-linux-imx <linux- [email protected]>; Bartosz Golaszewski
> > > <[email protected]>
> > > Subject: [EXT] Re: [PATCH v8 3/4] gpio: rpmsg: add generic rpmsg
> > > GPIO driver
> > > > Please explain how you would design your generic rpmsg-gpio driver
> > > > which is derived From gpio-virtio?
> > >
> > > We have already seen the virtio commands are pretty much identical
> > > to what i suggested.
> > >
> > > You could just replace virtqueue_add_sgs() with rpmsg_sendto() and
> > > reimplement
> > > virtio_gpio_request_vq() to be the callback registered with
> rpmsg_create_ept().
> > > The rest of basic GPIO handling should not need any changes at all.
> > >
> >
> > Creating endpoints and calling rpmsg_sendto() is only a small part of
> > the picture. You also need to manage the service announcement from the
> > remote side and handle asynchronous notification messages. That entire
> > flow is already implemented in the existing virtio_rpmsg_bus driver.
> > Re‑implementing those pieces just to mimic gpio‑virtio over RPMSG would
> essentially mean reinventing the wheel without any real benefit.
> >
>
> I can absolutely see a benefit to this, there are multiple different rpmsg
> backends
> supported in Linux, so a gpio-rpmsg driver could be used by any one of them.
>
> I don't see this to be a case of "reinventing the wheel". Instead we copy what
> looks to be a very functional wheel and make it fit rpmsg.
> This will result in some "duplication", but rpmsg already provide the life
> cycle
> management and has a clean send/callback interface, so there shouldn't be any
> inventing...
>
Interesting — could you walk me through how you’d structure the driver with the
new
proposal? I’d like to see how you would layer it conceptually.
The current RPMSG solution:
On Remoteprc On Linux
GPIOs -> RPMSG -> VIRTIO == VIRTIO -> RPMSG -> GPIO-RPMSG drivers
The VIRTIO solution:
On Remoteprc On Linux
GPIO -> VIRTIO == VIRTIO -> GPIO-VIRTIO driver
Your proposal:
On Remoteprc On Linux
GPIOs -> RPMSG -> VIRTIO == VIRTIO -> ???
Thanks,
Shenwei
> Similarly, I'm guessing that there's a firmware-side implementation of
> virtio-gpio
> in Zephyr, it should be straightforward to transplant this to the rpmsg
> interface.
>
> Regards,
> Bjorn
>
> > Thanks,
> > Shenwei
> >
> > > Interrupt support does however need some changes. The
> > > virtio_gpio_request_vq() replacement would need to see if the
> > > received message indicates an interrupt and call the equivalent of
> > > virtio_gpio_event_vq(), since rpmsg does not have a separate mechanism to
> deliver interrupts, unlike rpmsg.
> > >
> > > At a guess, 90% of the code would stay the same?
> > >
> > > Andrew
