PWM configuration on kernel 4

[mrtam...@gmail.com]

Hi,

I want to use 4 pwm signals, so my first step is load the files dtbo:

root@beaglebone:/sys/devices/platform/bone_capemgr# echo BB-PWM0 > slots

root@beaglebone:/sys/devices/platform/bone_capemgr# echo BB-PWM1 > slots

root@beaglebone:/sys/devices/platform/bone_capemgr# cat slots

 0: PF----  -1 

 1: PF----  -1 

 2: PF----  -1 

 3: PF----  -1 

 4: P-O-L-   0 Override Board Name,00A0,Override Manuf,cape-universaln

 5: P-O-L-   1 Override Board Name,00A0,Override Manuf,BB-PWM0

 6: P-O-L-   2 Override Board Name,00A0,Override Manuf,BB-PWM1

 

but when I try to very the correct pin configurations I found this:

root@beaglebone:/sys/devices/platform/bone_capemgr# cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pins | grep 950

pin 84 (44e10950.0) 00000037 pinctrl-single 

root@beaglebone:/sys/devices/platform/bone_capemgr# cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pins | grep 954

pin 85 (44e10954.0) 00000037 pinctrl-single 

So I open the dts file BB-PWM0-00A0.dts:

[...]

fragment@0 {

        target = <&am33xx_pinmux>;

            __overlay__ {

            pinctrl_spec: Panel_Pins {

                    pinctrl-single,pins = <

                        0x150 0x03 /* (A17) spi0_sclk.ehrpwm0A */

                        0x154 0x03 /* (B17) spi0_d0.ehrpwm0B */

                    >;

                };

            };

    };

[...]

It uses the correct 03 mode.

Why the pin use the wrong mode after the load of the device tree?

My OS is:

root@beaglebone:# uname -a

Linux beaglebone 4.1.22-ti-r59 #1 SMP Sat Apr 23 09:38:21 UTC 2016 armv7l GNU/Linux

Thanks

   Alessio

[Drew Fustini]

Since you have cape universal loaded, you should probably just use the
"config-pin" utility:

For example:
root@beaglebone:~# config-pin P9.14 pwm

Check out this blog post for more info:
https://briancode.wordpress.com/2015/01/06/working-with-pwm-on-a-beaglebone-black/

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