topic Re: Unable to get interrupts for rotary encoder in i.MX Processors

Unable to get interrupts for rotary encoder

Bhargava — Fri, 03 Dec 2021 05:01:42 GMT

Hi,

We are working with a Rotary encoder from Grayhill (62A15-02-040C).

The SOM we are using is SMARC conga-SMX8-Mini based on iMX8M Mini.

The Rotary encoder is interfaced to GPIOs 9 and 10 for Channel A and Channel B respectively.

The device tree for the same goes as below which is in reference with the document Documentation/devicetree/bindings/input/rotary-encoder.txt

rotary@0 {
compatible = "rotary-encoder";
gpios = <&gpio1 9 1>, <&gpio1 10 0>;
linux,axis = <0>; /* REL_X */
rotary-encoder,encoding = "gray";
rotary-encoder,relative-axis;
rotary-encoder,steps-per-period = <2>;
status = "okay";
};

We are using the generic rotary encoder driver available in the kernel (drivers/input/misc/rotary_encoder.c).

The driver probes successfully with device registration and interrupts allocation.

root@imx8mm-cgt-sx8m: cat /sys/kernel/debug/gpio
gpiochip0: GPIOs 0-31, parent: platform/30200000.gpio, 30200000.gpio:
gpio-1 ( |bkl pwm ) out hi
gpio-8 ( |enable ) out hi
gpio-9 ( |rotary@0 ) in lo IRQ ACTIVE LOW
gpio-10 ( |rotary@0 ) in lo IRQ
gpio-12 ( |regulator-usb ) out lo

And the interrupts being:

root@imx8mm-cgt-sx8m:~# cat /proc/interrupts

73: 0 gpio-mxc 9 Edge rotary-encoder
74: 0 gpio-mxc 10 Edge rotary-encoder

When tested with evtest tool no events are reported.

root@imx8mm-cgt-sx8m:~# evtest
No device specified, trying to scan all of /dev/input/event*
Available devices:
/dev/input/event0: 30370000.snvs:snvs-powerkey
/dev/input/event1: rotary@0
/dev/input/event2: gpio-keys
/dev/input/event3: bd718xx-pwrkey
/dev/input/event4: PixArt Dell MS116 USB Optical Mouse
Select the device event number [0-4]: 1
Input driver version is 1.0.1
Input device ID: bus 0x19 vendor 0x0 product 0x0 version 0x0
Input device name: "rotary@0"
Supported events:
Event type 0 (EV_SYN)
Event type 2 (EV_REL)
Event code 1 (REL_Y)
Properties:
Testing ... (interrupt to exit)

The issue is from the rotary_encoder.c driver none of the interrupt handlers like rotary_encoder_irq, rotary_encoder_half_period_irq.. are called.

Is there anything else to be done for the rotary encoder to work? On the hardware we checked for the pulses when encoder is rotated.

Please provide leads since the issue is hindering our further development.

SOC: iMX8M Mini

Yocto Zeus

Regards,

Bhargava

Re: Unable to get interrupts for rotary encoder

igorpadykov — Fri, 03 Dec 2021 09:58:48 GMT

Hi Bhargava

for producing gpio interrupts one can try below example (for can), add "interrupt-parent"

https://variwiki.com/index.php?title=VAR-SOM-MX8M-MINI-CAN

Best regards
igor

Re: Unable to get interrupts for rotary encoder

Bhargava — Fri, 03 Dec 2021 10:34:36 GMT

Hi Igor,

Thanks for responding.

I tried with the interrupt-parent but no success.

Here rotary encoder is the input device, the device generates signals on GPIOs which have to be interpreted as interrupts. Is my understanding correct? Please through some light on this.

Regards,

Bhargava

Re: Unable to get interrupts for rotary encoder

zoob — Sun, 22 May 2022 10:10:47 GMT

Hi Bhargava,

@Bhargava

I have the same problem .

please could you tell me how did you fix it ?

Thanks for your answer.

Re: Unable to get interrupts for rotary encoder

Bhargava — Tue, 24 May 2022 05:30:30 GMT

Hi Zoob,

In my case there was an issue in configuring GPIOs for rotary encoder.

GPIO configuration in device tree ("gpios" property in DTS) must be proper in order for rotary to work.

Regards,

Bhargava

Re: Unable to get interrupts for rotary encoder

zoob — Tue, 24 May 2022 06:15:53 GMT

Thanks.

I fixed it yesterday. Everythng is working fine.