can't get pwm to work in kernel 4.1, please help!

[M@ Dunlap]

Hello all, I'm trying with increasing desperation to get my BBB (that is running 4.1.4-1-ARCH) to use a PWM.  It used to work, but then I updated from 3.8 to 4.1 and now it's back to SNAFU.  I'm trying to get device trees to work, but I really, really don't get device tree overlays, I've read all the guides/docs and am still clueless.

My current best guess is to first load https://github.com/ProjectHexapod/bbbStuff/blob/master/overlays/am33xx_pwm-00A0.dts to activate pwm, and then load https://github.com/ProjectHexapod/bbbStuff/blob/master/overlays/thigh_bone-00A0.dts to configure all the pins.  Unfortunately when I do that and then try to echo something into pwmFolder/duty it tells me that the permission is denied.  I also don't understand why those need to be separate device tree overlays.

In attempting to isolate the problem I also came up with the following, but it gives the same permission denied errors.  I'm out of ideas, please send help!  Also, even if you don't know how to solve the problem, I'd also be interested to hear if there are style or high-level problems with my approach....

/dts-v1/;

/plugin/;

/ {

  compatible = "ti,beaglebone", "ti,beaglebone-black";

  /* identification */

  part-number = "test1";

  version = "00A0";

  exclusive-use =

    /* the pin header uses */

    "P8.13",

    /* the hardware IP uses */

    "ehrpwm2B";

  fragment@0 {

    target = <&epwmss0>;

    __overlay__ {

      status = "okay";

    };

  };

  fragment@1 {

    target = <&ehrpwm0>;

    __overlay__ {

      status = "okay";

    };

  };

  fragment@2 {

    target = <&epwmss1>;

    __overlay__ {

      status = "okay";

    };

  };

  fragment@3 {

    target = <&ehrpwm1>;

    __overlay__ {

      status = "okay";

    };

  };

  fragment@4 {

    target = <&epwmss2>;

    __overlay__ {

      status = "okay";

    };

  };

  fragment@5 {

    target = <&ehrpwm2>;

    __overlay__ {

      status = "okay";

    };

  };

fragment@6 {

    target = <&am33xx_pinmux>;

    __overlay__ {

      bs_pwm_P8_13_0x14: pinmux_bs_pwm_P8_13_0x14 {

        pinctrl-single,pins = <0x024 0x14>;

      };

    };

  };

  fragment@7 {

    target = <&ocp>;

    __overlay__ {

      bs_pwm_test_P8_13 {

        compatible  = "pwm_test";

        pwms    = <&ehrpwm2 1 500000 1>;

        pwm-names   = "PWM_P8_13";

        pinctrl-names = "default";

        pinctrl-0 = <&bs_pwm_P8_13_0x14>;

        enabled   = <1>;

        duty    = <0>;

        status    = "okay";

      };

    };

  };

};

[William Hermans]

Have you read this ?

https://github.com/beagleboard/bb.org-overlays

What version dtc are you using ? it must be 1.4.1 or greater.

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[M@]

Yes, and 1.4.1 respectively:

[root@stompyCentralControl sys]# zcat /proc/config.gz | grep CONFIG_BONE

CONFIG_BONE_CAPEMGR=y

[root@stompyCentralControl sys]# dtc -v

Version: DTC 1.4.1

[root@stompyCentralControl sys]# 

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[William Hermans]

hmm are there no PWM overlays already in that git ?

[William Hermans]

Ah, PWM may be one of those things that still needs work in kernel 4.x . . . Robert would probably know.

[Robert Nelson]

On Sun, Aug 23, 2015 at 4:06 PM, M@ Dunlap <matthew...@gmail.com> wrote:
> Hello all, I'm trying with increasing desperation to get my BBB (that is
> running 4.1.4-1-ARCH) to use a PWM. It used to work, but then I updated
> from 3.8 to 4.1 and now it's back to SNAFU. I'm trying to get device trees
> to work, but I really, really don't get device tree overlays, I've read all
> the guides/docs and am still clueless.
>
> My current best guess is to first load
> https://github.com/ProjectHexapod/bbbStuff/blob/master/overlays/am33xx_pwm-00A0.dts
> to activate pwm, and then load
> https://github.com/ProjectHexapod/bbbStuff/blob/master/overlays/thigh_bone-00A0.dts
> to configure all the pins. Unfortunately when I do that and then try to
> echo something into pwmFolder/duty it tells me that the permission is
> denied. I also don't understand why those need to be separate device tree
> overlays.
>
> In attempting to isolate the problem I also came up with the following, but
> it gives the same permission denied errors. I'm out of ideas, please send
> help! Also, even if you don't know how to solve the problem, I'd also be
> interested to hear if there are style or high-level problems with my
> approach....

pwm works fine, take a look at the bacon cape example we have for 4.1:

cape:
https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-BONE-BACONE-00A0.dts

and the script i used to test the pwm's

https://github.com/beagleboard/bb.org-overlays/blob/master/examples/BB-BONE-BACONE/example.sh

Regards,

--
Robert Nelson
https://rcn-ee.com/

[M@]

Thanks for those links!

I have two problems 1) /sys/class/pwm is empty, so I can't echo anything into a /export.  Could this be due to running Arch instead of Angstrom?

2) dtc is complaning that "#include" doesn't parse, saying "Error: BB-BONE-BACONE.dts:11.1-9 syntax error

FATAL ERROR: Unable to parse input tree"  Any ideas?

--M@

[M@]

Nevermind, I was just being an idiot, I think I've got it now thanks to those links, thanks for your help!!