On Wed, Sep 27, 2017 at 3:22 PM, William Hermans <[email protected]> wrote: > So a few things to note about pwm behavior on the latest stretch image > versus Jessie. > Obviously, Jessie by default runs an older kernel. 4.4.x versus 4.9.x. > > > First, > > Jessie: > root@wgd:~# uname -r > 4.4.68-ti-r111 > root@wgd:~# lsmod |grep pwm > pwm_tiehrpwm > > Stretch: > root@wgd:~# uname -r > 4.9.50-ti-r61 > root@wgd:~# lsmod |grep pwm /* No output */ > > Here, I'm thinking the PWM module is built into the kernel. Because I'm > running the same custom overlay on both boards, and both have a populated > sysfs entry for pwm. However there is a difference. > > Jessie: > root@wgd:~# ls /sys/class/pwm/pwmchip0 > device export npwm power pwm0 pwm1 subsystem uevent unexport > > Stretch: > root@wgd:~# ls /sys/class/pwm/pwmchip0 > device export npwm power pwm0 subsystem uevent unexport
Don't compare "pwmchipX's" directly, you need to dig into the symlink: root@beaglebone:/sys/class/pwm# ls -lh total 0 lrwxrwxrwx 1 root root 0 Oct 13 17:14 pwmchip0 -> ../../devices/platform/ocp/48300000.epwmss/48300200.pwm/pwm/pwmchip0 lrwxrwxrwx 1 root root 0 Oct 13 17:14 pwmchip2 -> ../../devices/platform/ocp/48300000.epwmss/48300100.ecap/pwm/pwmchip2 lrwxrwxrwx 1 root root 0 Oct 13 17:14 pwmchip3 -> ../../devices/platform/ocp/48302000.epwmss/48302200.pwm/pwm/pwmchip3 lrwxrwxrwx 1 root root 0 Oct 13 17:14 pwmchip5 -> ../../devices/platform/ocp/48304000.epwmss/48304200.pwm/pwm/pwmchip5 lrwxrwxrwx 1 root root 0 Oct 13 17:14 pwmchip7 -> ../../devices/platform/ocp/48304000.epwmss/48304100.ecap/pwm/pwmchip7 https://github.com/RobertCNelson/bb.org-overlays/blob/master/examples/cape-unversal-pwm.txt#L3-L9 Regards, -- Robert Nelson https://rcn-ee.com/ -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAOCHtYi2fp4%2By9XCS0Ceog3QUtOmUMbkjmi%2BnvOn%3DS86zPmNvQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
