Re: [PATCH] ARM: dts: qcom: msm8960: expressatt Add PWM vibrator
From: Rudraksha Gupta
Date: Thu Jan 29 2026 - 02:55:19 EST
Hello Konrad,
On 12/16/25 06:22, Konrad Dybcio wrote:
On 12/11/25 11:23 AM, Rudraksha Gupta via B4 Relay wrote:
From: Rudraksha Gupta <guptarud@xxxxxxxxx>Looks like this is because GP1_CLK does not implement .set_duty_cycle..
Add a pwm-vibrator to expressatt. Currently this vibrates only at 100%
Signed-off-by: Rudraksha Gupta <guptarud@xxxxxxxxx>
---
Add a pwm-vibrator to expressatt. Currently this vibrates only at 100%
Link:
- https://github.com/LineageOS/android_kernel_samsung_d2/blob/stable/cm-12.0-YNG4N/arch/arm/mach-msm/board-express.c#L1767
- https://github.com/LineageOS/android_kernel_samsung_d2/blob/stable/cm-12.0-YNG4N/drivers/motor/Makefile#L5
Test:
=====================
samsung-expressatt:~$ dmesg | grep vibra
[ 79.892226] input: pwm-vibrator as /devices/platform/vibrator/input/input4
samsung-expressatt:~$ fftest /dev/input/event4
Force feedback test program.
HOLD FIRMLY YOUR WHEEL OR JOYSTICK TO PREVENT DAMAGES
Device /dev/input/event4 opened
Features:
* Absolute axes:
[00 00 00 00 00 00 00 00 ]
* Relative axes:
[00 00 ]
* Force feedback effects types: Periodic, Rumble, Gain,
Force feedback periodic effects: Square, Triangle, Sine,
[00 00 00 00 00 00 00 00 00 00 03 07 01 00 00 00 ]
* Number of simultaneous effects: 16
Setting master gain to 75% ... OK
Uploading effect #0 (Periodic sinusoidal) ... OK (id 0)
Uploading effect #1 (Constant) ... Error: Invalid argument
Uploading effect #2 (Spring) ... Error: Invalid argument
Uploading effect #3 (Damper) ... Error: Invalid argument
The downstream driver you linked to does so in a terribly hacky way
(from the vibrator driver and not the clock driver):
https://github.com/LineageOS/android_kernel_samsung_d2/blob/cm-14.1/drivers/motor/immvibespi.c#L53
Upstream, we have an implementation for clk_rcg*2*_ops, whereas 8960
uses clk_rcg_ops.
They look very similar though, perhaps you can hack it up..
One thing to note is that you're passing GP1_CLK to the clk-pwm (as
you should), but we need to do clk_set_duty_cycle on its parent,
GP1_CLK*_SRC*. The framework will take care of this:
```
--- drivers/clk/clk.c
if (!core->ops->get_duty_cycle)
return clk_core_update_duty_cycle_parent_nolock(core);
```
so long as you add CLK_DUTY_CYCLE_PARENT to the child
[...]
Sorry for the delay, but I'm struggling to get this implemented. I have my in progress work here:
https://codeberg.org/LogicalErzor/linux/commit/4e7f94d9fdd1e4e1d688b2eb518494d710f157fb
I was able to get rid of the -16 error that was getting spammed when using fftest, but it is still showing
Uploading effect #1 (Constant) ... Error: Invalid argument
Uploading effect #2 (Spring) ... Error: Invalid argument
Uploading effect #3 (Damper) ... Error: Invalid argument
If you have any other insight on how to make the vibrator variable in intensity (it's still either 0% or 100%), please feel free to let me know. I will continue trying to hack away at it to see if I can get the variable intensity to work via fftest.
+ /* TODO: Vary the frequency besides being 0% or 100% */pinctrl-n
+ vibrator {
+ compatible = "pwm-vibrator";
+ pwms = <&gp1_pwm 0 54347 0>; /* ~18.4 kHz */
+ pwm-names = "enable";
+ enable-gpios = <&pm8921_gpio 4 GPIO_ACTIVE_HIGH>;
+ vcc-supply = <&vdd_haptics>;
+
+ pinctrl-names = "default";
+ pinctrl-0 = <&vib_pwm_gpio>;
pinctrl-names
please, both occurences
+ };Drop output-low, the driver should take care of setting the state
+
+ vdd_haptics: vdd-haptics-regulator {
+ compatible = "regulator-fixed";
+ regulator-name = "vdd_haptics";
+ gpio = <&tlmm 47 GPIO_ACTIVE_HIGH>;
+ enable-active-high;
+ regulator-boot-on;
+
+ pinctrl-names = "default";
+ pinctrl-0 = <&haptics_pwr_en>;
+ };
};
&gsbi2 {
@@ -241,6 +270,21 @@ touchkey_i2c_pins: touchkey-i2c-state {
bias-disable;
};
+ haptics_pwr_en: haptics-pwr-en-state {
+ pins = "gpio47";
+ function = "gpio";
+ drive-strength = <2>;
+ bias-disable;
+ output-low;
Konrad