One more thing, you may want to look at /driver/pinctrl/pinctrl-single.c as this is where the pinmux gets set.You could also use dynamic tracing to help find the responsible routine. Look in /Documentation/dynamic-debug-howto.txt. Probably a little bit of trial and error will be needed to narrow down this problem.
Regards, John > On Mar 30, 2016, at 3:45 PM, M House <mikehous...@gmail.com> wrote: > > Thanks for the reply John. I'm pretty new to modifying kernel modules and I > haven't worked with u-boot at all. I'm not sure at the moment when the GPIO > is modified but I think it happens whenever the system resets, most likely on > startup. Should I try a kernel dump right after I boot? > > Thanks, > Mike > > On Wednesday, March 30, 2016 at 2:03:58 PM UTC-7, john3909 wrote: > Well, that depends on how skilled you are at modifying u-boot and the linux > kernel? > > In each case, modify the code that toggles the GPIO pin by printing text to > the console when the GPIO you want is modified. You could always issue a > kernel dump when that GPIO is modified, which will list the call sequence > that causes the GPIO toggle. For the Kernel, I believe the code you want is > in drivers/gpio/gpio-omap.c, but I haven’t looked at u-boot in a while, but > it should be simple to find the equivalent code. > > If you had a decent JTAG emulator, you could simply set a breakpoint on the > GPIO toggle and then look at the call stack to see which routing is > responsible. > > Regards, > John > > > > >> On Mar 30, 2016, at 1:25 PM, M House <mikeh...@gmail.com <javascript:>> >> wrote: >> >> Hey everyone I'm still stuck as to why my beaglebone keeps changing the >> polarity to 1 on boot. I can go in and manually change it but it always >> resets after reboot. Should I maybe write a start up script to force the >> polarity to 0? I'd rather find the root cause rather than a hack but at >> this point anything that works is fine by me. >> >> Thank you >> >> On Saturday, March 19, 2016 at 11:30:58 PM UTC-7, M House wrote: >> I'm doing a project right now that involves using a micro servo. One is on >> port P8_13 and another on P9_14. >> >> Everytime I boot the beaglebone it gives me - error: Error enabling PWM >> controls: Error: ENOENT, no such file or directory >> '/sys/devices/ocp.3/bs_pwm_test_P9_14.15/polarity' >> >> When I check this file it shows a value of '1' inside of it. Where the same >> file for P8_13 shows a zero. When I change the P9_14 polarity file to 0 the >> servo works as intended. I'm really confused why the polarity is being set >> to 1 every time I boot the beaglebone. This also happens if I move the >> servo to P9_16. >> >> I did just upgrade from Debian 7.8 to 7.9 but I don't see how that would >> change the GPIO behavior. >> >> >> -- >> For more options, visit http://beagleboard.org/discuss >> <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...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. > > > -- > For more options, visit http://beagleboard.org/discuss > <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 > <mailto:beagleboard+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- 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. For more options, visit https://groups.google.com/d/optout.
