Gpio-ir module does not work

[nandlab]

Describe the bug

Although I enabled the gpio-ir dtoverlay, I cannot see any lirc device like /dev/lirc0.

Steps to reproduce the behaviour

Uncomment the line dtoverlay=gpio-ir,gpio_pin=17 in /boot/config.txt.

Device (s)

Raspberry Pi 4 Mod. B

System

cat /etc/rpi-issue:

Raspberry Pi reference 2022-01-28
Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, f01430c9d8f67a4b9719cc00e74a2079d3834d5d, stage4

vcgencmd version:

Oct 26 2022 11:09:05 
Copyright (c) 2012 Broadcom
version c72ad6b26ff40c91ef776b847436094ee63fabee (clean) (release) (start)

uname -a:

Linux nextpi 5.15.74-v7l+ #1595 SMP Wed Oct 26 11:05:08 BST 2022 armv7l GNU/Linux

Logs

dmesg:

[    5.396569] pinctrl-bcm2835 fe200000.gpio: pin gpio17 already requested by fe200000.gpio; cannot claim for ir-receiver@11
[    5.396600] pinctrl-bcm2835 fe200000.gpio: pin-17 (ir-receiver@11) status -22
[    5.396622] pinctrl-bcm2835 fe200000.gpio: could not request pin 17 (gpio17) from group gpio17  on device pinctrl-bcm2711
[    5.396643] gpio_ir_recv ir-receiver@11: Error applying setting, reverse things back

Additional context

No response

[nandlab]

It works with gpio 18 though.

[6by9]

It's told you pin gpio17 already requested by fe200000.gpio; cannot claim for ir-receiver@11

Please quote the full contents of your /boot/config.txt file, as something else is configured to use GPIO 17. (Nothing is configured to use GPIO 18, and therefore it loads).

[nandlab]

/boot/config.txt:

# For more options and information see
# http://rpf.io/configtxt
# Some settings may impact device functionality. See link above for details

# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1

# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
#overscan_left=16
#overscan_right=16
#overscan_top=16
#overscan_bottom=16

# uncomment to force a console size. By default it will be display's size minus
# overscan.
#framebuffer_width=1280
#framebuffer_height=720

# uncomment if hdmi display is not detected and composite is being output
#hdmi_force_hotplug=1

# uncomment to force a specific HDMI mode (this will force VGA)
#hdmi_group=1
#hdmi_mode=1

# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
#hdmi_drive=2

# uncomment to increase signal to HDMI, if you have interference, blanking, or
# no display
#config_hdmi_boost=4

# uncomment for composite PAL
#sdtv_mode=2

#uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

# Uncomment this to enable infrared communication.
dtoverlay=gpio-ir,gpio_pin=17
#dtoverlay=gpio-ir-tx,gpio_pin=18

# Additional overlays and parameters are documented /boot/overlays/README

# Enable audio (loads snd_bcm2835)
dtparam=audio=on

# Automatically load overlays for detected cameras
camera_auto_detect=1

# Automatically load overlays for detected DSI displays
display_auto_detect=1

# Enable DRM VC4 V3D driver
dtoverlay=vc4-kms-v3d
max_framebuffers=2

# Disable compensation for displays with overscan
disable_overscan=1

dtoverlay=pisound

[cm4]
# Enable host mode on the 2711 built-in XHCI USB controller.
# This line should be removed if the legacy DWC2 controller is required
# (e.g. for USB device mode) or if USB support is not required.
otg_mode=1

[all]

[pi4]
# Run as fast as firmware / board allows
arm_boost=1

[all]

How can I find out, which process uses a gpio pin?

[6by9]

You can use gpioinfo or look in /sys/kernel/debug/pinctrl/fe200000.gpio-pinctrl-bcm2711, however in your case it is fairly obvious as there is only one line different from normal - dtoverlay=pisound

https://github.com/raspberrypi/linux/blob/rpi-5.15.y/arch/arm/boot/dts/overlays/pisound-overlay.dts#L96 claims GPIO 17 for a button on the Pisound. If you don't actually have the Pisound connected, then remove the dtoverlay line.

[pelwell]

I'm pretty sure that this line (https://github.com/raspberrypi/linux/blob/rpi-5.15.y/arch/arm/boot/dts/overlays/pisound-overlay.dts#L104) is the reason the culprit isn't obvious, since it obscures what is really responsible for claiming the GPIO. I think the line could be deleted, since there is already another pinctrl reference associated with the sound card (https://github.com/raspberrypi/linux/blob/rpi-5.15.y/arch/arm/boot/dts/overlays/pisound-overlay.dts#L83), but it may also be necessary to move the pinctrl-names line (https://github.com/raspberrypi/linux/blob/rpi-5.15.y/arch/arm/boot/dts/overlays/pisound-overlay.dts#L83) as well.

[pelwell]

[ Comment typed into wrong issue deleted ]

[6by9]

Suffice to say that you're trying to use a GPIO already claimed by the Pisound card. Without the dtoverlay=pisound you should be able to load gpio-ir on GPIO 17.

[nandlab]

I disabled dtoverlay=pisound and now gpio-ir works with GPIO 17. Thank you!