On 11/24/2017 06:37 AM, Greg Gallagher wrote: > Hi, > I'm finishing up my work on a patch to add a RTDM gpio driver for > the zynq-7000 platform. I ran into a situation where I needed to call > gpio_request in gpio-core because the zynq gpio driver uses the > gpio_request function to enable the gpio pins on the board. > A side effect that I found when testing is that the driver will fail to > load > if another application has exported a gpio pin via sysfs and likewise sysfs > won't allow anyone to export gpio pins once the rtdm gpio driver has been > loaded. > My implementation calls gpio_request on each pin as they are registered > under /dev/rtdm. > I'm not sure if the above is an issue or not, if the RTDM driver has > claimed the > gpio pins then I think it would make sense for them not to be accessible by > applications > via sysfs. If my assumption is not correct then maybe one option could be > to only call gpio_request on each pin as need, maybe via ioctl? > > Any guidance would be appreciated, >
gpio-core deals with entire GPIO controllers, so claiming every pin from every bank on the controller for rt usage unconditionally seems overkill. The ioctl option seems a better option, but then you would have to be careful about not conflicting with request_gpio_irq() which does request input pins. rtdm_gpio_chan->requested tells whether a pin as already been claimed. -- Philippe. _______________________________________________ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai
