[PATCH v8 3/4] gpio: rpmsg: add generic rpmsg GPIO driver

[Shenwei Wang]

> -----Original Message-----
> From: Bjorn Andersson <andersson at kernel.org>
> Sent: Monday, February 23, 2026 8:43 AM
> To: Arnaud POULIQUEN <arnaud.pouliquen at foss.st.com>
> Cc: Linus Walleij <linusw at kernel.org>; Shenwei Wang
> <shenwei.wang at nxp.com>; Andrew Lunn <andrew at lunn.ch>; Bartosz
> Golaszewski <brgl at kernel.org>; Jonathan Corbet <corbet at lwn.net>; Rob Herring
> <robh at kernel.org>; Krzysztof Kozlowski <krzk+dt at kernel.org>; Conor Dooley
> <conor+dt at kernel.org>; Mathieu Poirier <mathieu.poirier at linaro.org>; Frank Li
> <frank.li at nxp.com>; Sascha Hauer <s.hauer at pengutronix.de>; Shuah Khan
> <skhan at linuxfoundation.org>; linux-gpio at vger.kernel.org; linux-
> doc at vger.kernel.org; linux-kernel at vger.kernel.org; Pengutronix Kernel Team
> <kernel at pengutronix.de>; Fabio Estevam <festevam at gmail.com>; Peng Fan
> <peng.fan at nxp.com>; devicetree at vger.kernel.org; linux-
> remoteproc at vger.kernel.org; imx at lists.linux.dev; linux-arm-
> kernel at lists.infradead.org; dl-linux-imx <linux-imx at nxp.com>; Bartosz
> Golaszewski <brgl at bgdev.pl>
> Subject: [EXT] Re: [PATCH v8 3/4] gpio: rpmsg: add generic rpmsg GPIO driver
> On Mon, Feb 23, 2026 at 03:24:43PM +0100, Arnaud POULIQUEN wrote:
> > On 2/22/26 15:48, Linus Walleij wrote:
> > > On Fri, Feb 20, 2026 at 7:57 PM Shenwei Wang <shenwei.wang at nxp.com>
> wrote:
> [..]
> > >
> > > Is it generic? If it is not, let's call it "NXP rpmsg GPIO driver"
> > > and rename files etc accordingly. Maybe it can share code with the
> > > actual generic RPMSG driver once that arrives, that is more of a library
> question.
> >
> > I would like to (re)express my concerns regarding the creation of an
> > NXP-specific driver. To clarify my concerns, ST, like probably some
> > other SoC vendors, has rpmsg-gpio and rpmsg-i2c drivers in downstream
> > with plans to upstream them.
> >
> > If we proceed in this direction:
> >
> > -Any vendor wishing to upstream an rpmsg-gpio driver might submit
> > their own platform-specific version.
> >
> > - If NXP upstreams other rpmsg drivers, these will likely remain
> > NXP-centric to maintain compatibility with their legacy firmware and
> > the nxp-rpmsg-gpio driver, leading to platform-specific versions in several
> frameworks.
> >
> > - The implementation will impact not only the Linux side but also the
> > remote side. Indeed, some operating systems like Zephyr or NuttX
> > implement the rpmsg device side (Zephyr already implements the
> > rpmsg-tty)
> >
> > Maintaining a generic approach for RPMsg, similar to what is done for
> > Virtio, seems to me a more reliable solution, even though it may
> > induce some downstream costs (ST would also need to break
> > compatibility with legacy ST remote proc firmware).
> >
> 
> Could the virtio-based mechanism be used directly (without rpmsg)?
> 

Technically, yes—it's possible to use the virtio mechanism directly without rpmsg.
It’s a bit like talking straight to the IP layer without involving TCP or UDP: doable, but 
at a lower‑level approach.

As for the idea of gpio‑virtio, which could be an optional solution that certain customers 
might prefer. I recall hearing this idea from Mathieu originally, though I’m not sure whether 
he plans to implement it.

As the chip vendor, NXP’s role is to provide all possible options and let customers choose 
the approach that best fits their needs; we don’t make that decision for them.

Thanks,
Shenwei

> 
> If not, it would be good to derive a generic rpmsg-gpio protocol from the virtio
> protocol, and land implementations of this in e.g. Linux and Zephyr to establish
> that option.
> 
> Regards,
> Bjorn
> 
> >
> > In the end, I am just trying to influence the direction for RPMsg, but
> > based on the discussions in this thread, it seems others share similar
> > expectations, which should probably be taken into account as well.
> >
> > Thanks and Regards,
> > Arnaud
> >
> >
> > I just want to
> >
> > >
> > > Yours,
> > > Linus Walleij
> >