Hello,
Setup
Yocto branch: Kirkstone (honister back-ports disabled)
Layers / commits
meta-odroid 06f8d2c (last week’s master)
poky kirkstone (bitbake 2.2.0)
Kernel: linux = v5.15
What I changed so far
Enabled the driver
Added a linux-hardkernel_%.bbappend with:
CONFIG_PWM=y
CONFIG_PWM_MESON=y
Patched the Device Tree (added a new layer to patch in yocto using devtool):
From 9f296f4b8f636b12ef8c0a4720cf0d25d9eeb810 Mon Sep 17 00:00:00 2001
From: OpenEmbedded <oe.patch@oe>
Date: Thu, 17 Jul 2025 15:50:18 -0400
Subject: [PATCH] some changes to source for pwm
---
arch/arm64/boot/dts/amlogic/meson-gx.dtsi | 2 +-
.../arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts | 14 ++++++++++++++
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/boot/dts/amlogic/meson-gx.dtsi b/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
index 32cc9fab4490..f7abfd4746d2 100644
--- a/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
@@ -330,7 +330,7 @@ pwm_ab: pwm@8550 {
compatible = "amlogic,meson-gx-pwm", "amlogic,meson-gxbb-pwm";
reg = <0x0 0x08550 0x0 0x10>;
#pwm-cells = <3>;
- status = "disabled";
+ status = "okay";
};
pwm_cd: pwm@8650 {
diff --git a/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts b/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
index 201596247fd9..0f5e52e7096c 100644
--- a/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
+++ b/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
@@ -416,3 +416,17 @@ &usb0 {
&usb1 {
status = "okay";
};
+
+&pwm_ab {
+ status = "okay";
+ pinctrl-names = "default";
+ pinctrl-0 = <&pwm_a_x_pins>;
+};
+
+&pinctrl {
+ pwm_a_x_pins: pwm_a_x {
+ groups = "pwm_a_x";
+ functions = "pwm_a_x";
+ bias-pull-disable;
+ };
+};
Symptoms
modprobe pwm-meson dosen't loads, nothing in dmesg. But the file are here :
root@odroid-c2:~# dmesg | grep pwm
root@odroid-c2:~# ls /sys/class/pwm*
pwmchip0
root@odroid-c2:~# ls /sys/class/pwm/pwmchip0/
device export npwm power subsystem uevent unexport
root@odroid-c2:~# modprobe pwm-meson
root@odroid-c2:~# dmesg | grep pwm
root@odroid-c2:~# ls /sys/class/pwm/pwmchip0/
device export npwm power subsystem uevent unexport
root@odroid-c2:~# echo 0 > /sys/class/pwm/pwmchip0/export
root@odroid-c2:~# ls /sys/class/pwm/pwmchip0/pwm0/
capture duty_cycle enable period polarity power uevent
/sys entries:
/sys/class/pwm/pwmchip0/
├── export
├── npwm
├── device
├── power
├── subsystem
├── uevent
├── unexport
└── pwm0/
├── freq0
├── duty0
└── enable0
I run (root):
root@odroid-c2:~# echo 20000000 > /sys/class/pwm/pwmchip0/pwm0/period
root@odroid-c2:~# echo 1500000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle
root@odroid-c2:~# echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable
but nothing happen.
Questions
Has anyone successfully driven hardware PWM on the C2 with current meta-odroid + Kirkstone?
Any known quirks with the pinctrl or the pwm-meson driver on kernels ≥ 5.15?
Sample DTS snippet or working .bbappend would be greatly appreciated!
Thanks in advance.
Krum
