Re: [beagleboard] Re: PWM Pin Error on Boot

2016-03-30 Thread John Syne 
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  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  
>> 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 
>> 
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> 
> 
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Re: [beagleboard] Re: PWM Pin Error on Boot

2016-03-30 Thread M House 
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  
> 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.
>>
>>
> -- 
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>
>
>

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Re: [beagleboard] Re: PWM Pin Error on Boot

2016-03-30 Thread John Syne 
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  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 
> 
> --- 
> 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 
> .

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[beagleboard] Re: PWM Pin Error on Boot

2016-03-30 Thread M House 
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.
>
>

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[beagleboard] Re: PWM Pin Error on Boot

2016-03-20 Thread M House 
I should clarify that it is every time I start my node.js server file that 
a has a required module that uses P9_14.  I can manually change the 
polarity to 0 but it resets every time I reboot.

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.
>
>

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