[SOLVED] Zero 3E PWM GPIO under Kernel 6.1 Ubuntu

ioncube · March 28, 2025, 1:10am

My Host

OS: Armbian (24.8.4) aarch64 
Host: Radxa ZERO 3 
Kernel: 6.1.75-vendor-rk35xx 
Uptime: 1 hour, 27 mins 
Packages: 1011 (dpkg) 
Shell: bash 5.2.21 
Terminal: /dev/pts/1 
CPU: (4) @ 2.000GHz 
Memory: 1313MiB / 3732MiB

Overlays I have activated (as per github & .dts contents these are for Zero 3)

overlays=npu-enable pwm12-m1 pwm13-m1 pwm14-m0 pwm14-m1 pwm15-m1 pwm8-m0 pwm9-m0

After this I can find

ls /sys/class/pwm/
pwmchip0  pwmchip1  pwmchip2  pwmchip3  pwmchip4  pwmchip5
cat /sys/class/pwm/pwmchip{0,1,2,3,4,5}/device/modalias 
of:NpwmT(null)Crockchip,rk3568-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3568-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3568-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3568-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3568-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3568-pwmCrockchip,rk3328-pwm

However, there is something wrong

cat /sys/kernel/debug/pwm
platform/fe700030.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/fe700020.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/fe700010.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/fe700000.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/fe6f0010.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/fe6f0000.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

The output should be something like How to use any PWM on Radxa Zero (sysfs)

I have also compiled mraa However per official documentation it will not work under kernel 6.1 https://docs.radxa.com/en/zero/zero3/app-development/mraa#pwm

I can run CLI commands properly though

mraa-gpio list
01         3V3: 
02          5V: 
03    GPIO0_D1: I2C  UART 
04          5V: 
05    GPIO0_D0: I2C  UART 
06         GND: 
07    GPIO3_C4: GPIO PWM  
08    GPIO0_D1: UART 
09         GND: 
10    GPIO0_D0: UART 
11    GPIO3_A1: GPIO 
12    GPIO3_A3: GPIO 
13    GPIO3_A2: GPIO 
14         GND: 
15   GPIO03_B0: GPIO 
16   GPIO03_B1: GPIO PWM  UART 
17         3V3: 
18    GPIO3_B2: GPIO PWM  UART 
19    GPIO4_C3: GPIO SPI  
20         GND: 
21    GPIO4_C5: GPIO SPI  PWM  UART 
22    GPIO3_C1: GPIO 
23    GPIO4_C2: GPIO SPI  PWM  
24    GPIO4_C6: GPIO SPI  PWM  UART 
25         GND: 
26    GPIO4_D1: GPIO 
27    GPIO4_B2: GPIO I2C  
28    GPIO4_B3: GPIO I2C  
29    GPIO3_B3: GPIO 
30         GND: 
31    GPIO3_B4: GPIO 
32    GPIO3_C2: GPIO UART 
33    GPIO3_C3: GPIO UART 
34         GND: 
35    GPIO3_A4: GPIO 
36    GPIO3_A7: GPIO 
37    GPIO1_A4: 
38    GPIO3_A6: GPIO 
39         GND: 
40    GPIO3_A5: GPIO 

mraa-gpio version
Version v2.2.0 on Radxa ZERO 3

Any help will be highly welcomed

In examples folder of mraa I tried both pwm.c & pwm.py both gave this error

Error initialising PWM on pin

I did change PIN# for instance in python code

import mraa
import time

# initialise PWM
x = mraa.Pwm(23) #in my case it will be 7,23,24...

# set PWM period
x.period_us(700)

# enable PWM
x.enable(True)

value= 0.0

while True:
    # write PWM value
    x.write(value)

    time.sleep(0.05)

    value = value + 0.01
    if value >= 1:
        value = 0.0

avaf · March 23, 2025, 5:42pm

Nothing wrong with your output, you need to export it and set the values.
I’m not running kernel 6.1.x on my 3W, but I’m running 6.1.x in Rock5-lite, where you can use the PWM pins the same way. Take this as an example:

root@rock5c-lite:/home/rock# cat /sys/class/pwm/pwmchip{0,1,2,3,4}/device/modalias
of:NpwmT(null)Crockchip,rk3588-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3588-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3588-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3588-pwmCrockchip,rk3328-pwm
of:NpwmT(null)Crockchip,rk3588-pwmCrockchip,rk3328-pwm
root@rock5c-lite:/home/rock# cat /sys/kernel/debug/pwm
platform/febd0030.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/febd0020.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/fd8b0030.pwm, 1 PWM device
 pwm-0   (pwm-fan             ): requested enabled period: 60000 ns duty: 59999 ns polarity: normal

platform/fd8b0010.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/fd8b0000.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal
root@rock5c-lite:/home/rock# echo 0 > /sys/class/pwm/pwmchip1/export
root@rock5c-lite:/home/rock# cat /sys/kernel/debug/pwm
platform/febd0030.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/febd0020.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal

platform/fd8b0030.pwm, 1 PWM device
 pwm-0   (pwm-fan             ): requested enabled period: 60000 ns duty: 59999 ns polarity: normal

platform/fd8b0010.pwm, 1 PWM device
 pwm-0   (sysfs               ): requested period: 0 ns duty: 0 ns polarity: inverse

platform/fd8b0000.pwm, 1 PWM device
 pwm-0   ((null)              ): period: 0 ns duty: 0 ns polarity: normal
root@rock5c-lite:/home/rock#

T

Nasca · March 24, 2025, 2:14am

Due to changes in the pwmchip driver, the PWM function of the MRAA does not work properly on the 6.1 kernel.

Nasca · March 24, 2025, 2:24am

The current pwm driver assigns the pwm chip id dynamically, rather than statically as in the past.

github.com

torvalds/linux/blob/master/drivers/pwm/core.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Generic pwmlib implementation
 *
 * Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
 * Copyright (C) 2011-2012 Avionic Design GmbH
 */

#define DEFAULT_SYMBOL_NAMESPACE "PWM"

#include <linux/acpi.h>
#include <linux/module.h>
#include <linux/idr.h>
#include <linux/of.h>
#include <linux/pwm.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/device.h>

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alansrobotlab · March 25, 2025, 4:57pm

Hey @ioncube I know it’s not related to your question, but how are you running your board at 2.0Ghz under Armbian?

ioncube · March 28, 2025, 8:16am

@avaf @Nasca

python-periphery works instead of mraa

Thanks for your input. I have been successful in running PWM under Kernel 6.1
Instructions are here:

https://www.reddit.com/r/OrangePI/comments/1jl963x/success_activating_using_pwm_on_opi_3b_radxa_3e/

ioncube · March 28, 2025, 1:15am

My github account which had a wealth of knowledge is being suspended temporarily. I am resolving it at the moment. You can overclock both CPU & GPU

I am attaching overclock .dtb & .dts In my configuration only CPU is overclocked

rk3566-radxa-zero3.zip (62.4 KB)

Nasca · March 28, 2025, 1:51am

Thank you for sharing.