[PATCH v5 0/5] Enable Remote GPIO over RPMSG on i.MX Platform

[Shenwei Wang]

Hi Arnaud,

> -----Original Message-----
> From: Arnaud POULIQUEN <arnaud.pouliquen at foss.st.com>
> Sent: Thursday, November 6, 2025 4:17 AM
> To: Shenwei Wang <shenwei.wang at nxp.com>; Peng Fan <peng.fan at nxp.com>;
> Bjorn Andersson <andersson at kernel.org>; Mathieu Poirier
> <mathieu.poirier at linaro.org>; Rob Herring <robh at kernel.org>; Krzysztof
> Kozlowski <krzk+dt at kernel.org>; Conor Dooley <conor+dt at kernel.org>; Shawn
> Guo <shawnguo at kernel.org>; Sascha Hauer <s.hauer at pengutronix.de>;
> Jonathan Corbet <corbet at lwn.net>; Linus Walleij <linus.walleij at linaro.org>;
> Bartosz Golaszewski <brgl at bgdev.pl>
> Cc: Pengutronix Kernel Team <kernel at pengutronix.de>; Fabio Estevam
> <festevam at gmail.com>; linux-remoteproc at vger.kernel.org;
> devicetree at vger.kernel.org; imx at lists.linux.dev; linux-arm-
> kernel at lists.infradead.org; linux-kernel at vger.kernel.org; linux-
> doc at vger.kernel.org; dl-linux-imx <linux-imx at nxp.com>; Randy Dunlap
> <rdunlap at infradead.org>; Andrew Lunn <andrew at lunn.ch>; linux-
> gpio at vger.kernel.org
> Subject: [EXT] Re: [PATCH v5 0/5] Enable Remote GPIO over RPMSG on i.MX
> Platform
> 
> Hi Shenwei,
> 
> On 11/5/25 15:12, Shenwei Wang wrote:
> > Hi Arnaud,
> >
> >> -----Original Message-----
> >>
> >> On 11/5/25 02:12, Peng Fan wrote:
> >>> Hi Shenwei
> >>>
> >>>> Subject: [PATCH v5 0/5] Enable Remote GPIO over RPMSG on i.MX
> >>>> Platform
> >>>>
> >>>> Support the remote devices on the remote processor via the RPMSG
> >>>> bus on i.MX platform.
> >>>>
> >>>
> >>> I have not look into the details of new version, but before that,
> >>> just want to check, have we agreed on what Arnaud suggested?
> >>> or continue to proceed to be this as i.MX specific?
> >>
> >> Thanks, Peng, for pointing this out. Regarding the V3 discussions, it
> >> seems that I am not the only one suggesting a generic driver.
> >>
> >
> > As I mentioned before, the only i.MX-specific part is the transport protocol over
> the RPMSG bus.
> > In this v5 patches, we’ve included detailed documentation for the
> > protocol in a separate file. Any platform that follows the same protocol should
> work right out of the box.
> >
> > If you spot anything that could be improved, please let me know!
> 
> My concerns remain the same as those shared previously:
> 
> 1) The simpler one: gpio-imx-rpmsg.c should be renamed to gpio-rpmsg.c.
> 

Agree. Will fix it in the next version.

> 2) The more complex one: the driver should be independent of the remoteproc
> driver. The rpmsg protocol relies on virtio and can be used in contexts other than
> remoteproc. In other words, the struct rpmsg_driver and its associated
> operations should be defined within the rpmsg-gpio driver, not in the remoteproc
> driver.
> 

The GPIO driver operates independently of the remoteproc driver. It functions based 
on the defined GPIO-RPMSG transport protocol. Any remoteproc that supports 
this protocol can exchange data with the GPIO driver via the underlying rpmsg bus. 
Placing the rpmsg_driver (which manages the rpmsg channel) within the remoteproc 
driver is more logical, as rpmsg channels run on the rpmsg bus. This bus is defined inside 
the remoteproc device tree node and is populated by the corresponding remoteproc driver. 

Thanks,
Shenwei

> 
> Thanks,
> Arnaud
> 
> >
> > Thanks,
> > Shenwei
> >
> >> Thanks,
> >> Arnaud
> >>
> >>>
> >>> Thanks
> >>> Peng.
> >