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

[Shenwei Wang]

> -----Original Message-----
> From: Andrew Lunn <andrew@xxxxxxx>
> Sent: Thursday, February 19, 2026 7:27 AM
> To: Arnaud POULIQUEN <arnaud.pouliquen@xxxxxxxxxxx>
> Cc: Shenwei Wang <shenwei.wang@xxxxxxx>; Linus Walleij
> <linusw@xxxxxxxxxx>; Bartosz Golaszewski <brgl@xxxxxxxxxx>; Jonathan Corbet
> <corbet@xxxxxxx>; Rob Herring <robh@xxxxxxxxxx>; Krzysztof Kozlowski
> <krzk+dt@xxxxxxxxxx>; Conor Dooley <conor+dt@xxxxxxxxxx>; Bjorn Andersson
> <andersson@xxxxxxxxxx>; Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>; Frank Li
> <frank.li@xxxxxxx>; Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>; Shuah Khan
> <skhan@xxxxxxxxxxxxxxxxxxx>; linux-gpio@xxxxxxxxxxxxxxx; linux-
> doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Pengutronix Kernel Team
> <kernel@xxxxxxxxxxxxxx>; Fabio Estevam <festevam@xxxxxxxxx>; Peng Fan
> <peng.fan@xxxxxxx>; devicetree@xxxxxxxxxxxxxxx; linux-
> remoteproc@xxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; Bartosz
> Golaszewski <brgl@xxxxxxxx>
> Subject: [EXT] Re: [PATCH v8 3/4] gpio: rpmsg: add generic rpmsg GPIO driver
> 
> > > +   if (sync) {
> > > +           err = wait_for_completion_timeout(&info->cmd_complete,
> > > +                                             msecs_to_jiffies(RPMSG_TIMEOUT));
> > > +           if (err == 0) {
> > > +                   dev_err(&info->rpdev->dev, "rpmsg_send timeout!\n");
> > > +                   return -ETIMEDOUT;
> >
> > strange condition you return an error if err == 0, for redability use 'ret'
> > variable or simply:
> >
> >               if(!wait_for_completion_timeout(&info->cmd_complete,
> >                                 msecs_to_jiffies(RPMSG_TIMEOUT)) {
> >                       dev_err(&info->rpdev->dev, "rpmsg_send timeout!\n");
> >                       return -ETIMEDOUT;
> >               }
> 
> This will be from a comment i made. It appears that
> do_wait_for_common() can return -ERESTARTSYS. I assume that should be
> returned to user space?
> 

It looks like there might be a bit of confusion around what wait_for_completion_timeout() 
actually returns. That function never returns -ERESTARTSYS. Instead, its behavior is pretty 
simple:

- 0 means the wait timed out
- A positive value means the completion happened (the value is just the remaining jiffies)

So the driver returns the timeout error, and the upper application can decide how it wants
to handle that situation, for example restart or ignore.

Thanks,
Shenwei

>         Andrew