ipipe-arm64 kernel issue

Greg Gallagher greg at embeddedgreg.com
Thu Dec 13 21:14:43 CET 2018


Hi Steve,

On Thu, Dec 13, 2018 at 3:04 PM Steve Pavao via Xenomai
<xenomai at xenomai.org> wrote:
>
> > On Dec 13, 2018, at 7:50 AM, Steve Pavao <stevep at korgrd.com> wrote:
>
> > As I continue to bring up my app, I notice I’m having a segfault (SIGSEGV) trying to access the general purpose IO pins.
> >
> > I notice that /dev/gpiomem is missing from the environment.
>
> > I am using the dtb from the ipipe-arm64 build.
> >
> > Steve Pavao
> > Korg R&D
>
> I learned there is a kernel config option to load a driver for this.  The config option is named CONFIG_BCM2835_DEVGPIOMEM.  It is set to Y in the config.  In the raspberrypi-linux kernel, the driver is here https://github.com/raspberrypi/linux/tree/rpi-4.14.y/drivers/char/broadcom , but I don’t see the file in the ipipe-arm64 repo.

If it's not in the mainline repo then it won't be in the arm64 ipipe tree.
>
> Do the ipipe-arm repos tend to allow support for vendor-specific drivers for features like this, and if so, would the Xenomai team be willing to add the gpiomem driver to the ipipe-arm64 kernel build?  I don’t know the policy for something like this, so thought I would ask to add support for it, and see what is customary.
>
Do the pins need realtime response?  If you don't need realtime
response have you looked at using the /dev/gpiochipX character driver?
 If they need to be realtime we have a rtdm gpio driver that can be
used to control the pins.

> Steve Pavao
> Korg R&D
>
>
>

-Greg



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