Error when starting PRU: "-bash: echo: write error: Invalid argument"

General Discussion
1

Hi,

I am getting the following error when starting the PRU on a Beaglebone Black. The Debian version is Buster IoT 10.3 with all packages up to date. I am using the PRU_gpioToggle example in the ti pru software support package. Also tried other examples, but I get the same error.

root@beaglebone:/home/debian# cp PRU_gpioToggle.out /lib/firmware/
root@beaglebone:/home/debian# echo 'PRU_gpioToggle.out' > /sys/class/remoteproc/remoteproc1/firmware
root@beaglebone:/home/debian# echo 'start' > /sys/class/remoteproc/remoteproc1/state
bash: echo: write error: Invalid argument

From dmesg:

[   77.087964] pru-rproc 4a334000.pru: PRU rproc node pru@4a334000 probed successfully
[   77.101753] pru-rproc 4a338000.pru: PRU rproc node pru@4a338000 probed successfully
[  199.843143] remoteproc remoteproc1: powering up 4a334000.pru
[  199.853266] remoteproc remoteproc1: Booting fw image PRU_gpioToggle.out, size 30172
[  199.853355] remoteproc remoteproc1: Boot failed: -22

Kernel Version:

Linux beaglebone 4.19.94-ti-r42 #1buster SMP PREEMPT Tue Mar 31 19:38:29 UTC 2020 armv7l GNU/Linux

uEnv.txt Configuration:

disable_uboot_overlay_video=1
uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-19-TI-00A0.dtbo

I’ve also tried running this on a pocketbeagle, but I am getting the same result. Am I missing something?
Any help will be appreciated.

Thanks!

2

There might be a problem with the Kernel and pru software support package version compatibility.

When I started out working I noticed that the preinstalled pssp in /usr/lib/ti/pru-software-support-package didn’t work (don’t remember the exact error that I got) so it might be the same thing that is happening to you right now. I solved this by downloading a fresh version that did work.

git clone --depth=1 --branch v5.9.0 git://git.ti.com/pru-software-support-package/pru-software-support-package.git

Note that I am getting version 5.9.0 and not the latest 6.X.X as version 6.0.0 dropped support for Kernels older than 5.10. If you’re using newer Kernels you obviously have to use those instead.

1 Like
3

Thanks @lopatin. I compiled the code using the PRU support package V5.9.0 and it resolved my problem. Thanks, much appreciated!