-----Original Message-----
From: Bjorn Andersson <andersson@kernel.org>
Sent: Wednesday, February 25, 2026 9:53 AM
To: Shenwei Wang <shenwei.wang@nxp.com>
Cc: Andrew Lunn <andrew@lunn.ch>; Mathieu Poirier
[off-list ref]; Arnaud POULIQUEN
[off-list ref]; Linus Walleij [off-list ref]; Bartosz
Golaszewski [off-list ref]; Jonathan Corbet [off-list ref]; Rob Herring
[off-list ref]; Krzysztof Kozlowski [off-list ref]; Conor Dooley
[off-list ref]; Frank Li [off-list ref]; Sascha Hauer
[off-list ref]; Shuah Khan [off-list ref]; linux-
gpio@vger.kernel.org; linux-doc@vger.kernel.org; linux-kernel@vger.kernel.org;
Pengutronix Kernel Team [off-list ref]; Fabio Estevam
[off-list ref]; Peng Fan [off-list ref];
devicetree@vger.kernel.org; linux-remoteproc@vger.kernel.org;
imx@lists.linux.dev; linux-arm-kernel@lists.infradead.org; dl-linux-imx <linux-
imx@nxp.com>; Bartosz Golaszewski [off-list ref]
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:

quoted

quoted

-----Original Message-----
From: Andrew Lunn <andrew@lunn.ch>
Sent: Tuesday, February 24, 2026 4:15 PM
To: Shenwei Wang <shenwei.wang@nxp.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>; Bjorn Andersson
[off-list ref]; Arnaud POULIQUEN
[off-list ref]; Linus Walleij [off-list ref];
Bartosz Golaszewski [off-list ref]; Jonathan Corbet
[off-list ref]; Rob Herring [off-list ref]; Krzysztof Kozlowski
[off-list ref]; Conor Dooley [off-list ref]; Frank Li
[off-list ref]; Sascha Hauer [off-list ref]; Shuah
Khan [off-list ref]; linux- gpio@vger.kernel.org;
linux-doc@vger.kernel.org; linux-kernel@vger.kernel.org; Pengutronix
Kernel Team [off-list ref]; Fabio Estevam
[off-list ref]; Peng Fan [off-list ref];
devicetree@vger.kernel.org; linux-remoteproc@vger.kernel.org;
imx@lists.linux.dev; linux-arm-kernel@lists.infradead.org;
dl-linux-imx <linux- imx@nxp.com>; Bartosz Golaszewski
[off-list ref]
Subject: [EXT] Re: [PATCH v8 3/4] gpio: rpmsg: add generic rpmsg
GPIO driver

quoted

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().

quoted

quoted

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.

quoted

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

quoted

Thanks,
Shenwei

quoted

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.

quoted

quoted

At a guess, 90% of the code would stay the same?

   Andrew