On Thu, Mar 26, 2020 at 10:59 AM John Allwine <j...@allwinedesigns.com> wrote:
> I'm happy to leave the pinmux alone, but if all I'm doing is reading or > writing to the GPIO can I do so from /dev/mem? > > According to this post, it's about 1000x faster: > http://chiragnagpal.com/examples.html > > It's also how hal_bb_gpio is implemented: > https://github.com/machinekit/machinekit-hal/blob/master/src/hal/drivers/hal_bb_gpio/hal_bb_gpio.c > > If necessary, it could be rewritten to use sysfs, but if it means being > 1000x slower, that's not ideal. > I've used /dev/mem to access(read, and write), registers on the BBB and I do agree. It is much faster. The reason why it's bad to use /dev/mem . . . is that there is no way for the kernel to know what state a given "device" is in. That is, without a physical read. Potentially, this could be bad. Especially if another driver or application has access to the given hardware register. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CALHSORqqqeLqoCbGh3r%2BAkVJQFBnX3akFEexCQELKVH%2Bw5GZEA%40mail.gmail.com.
