Official Display • Re: Raspberry Pi 4 with official touchscreen no display after update 02/02/2024

There is nothing I can see related to the touch panel in the kernel log (just lots of iptables entries), but it only goes back a couple of hours so probably not long enough now.

However, this is in the log and I don't know what it is:

Code:

[Wed Feb 21 10:33:16 2024] usb 1-1.4: USB disconnect, device number 3[Wed Feb 21 10:33:17 2024] usb 1-1.4: new full-speed USB device number 4 using xhci_hcd[Wed Feb 21 10:33:17 2024] usb 1-1.4: New USB device found, idVendor=4c4a, idProduct=4155, bcdDevice= 1.00[Wed Feb 21 10:33:17 2024] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3[Wed Feb 21 10:33:17 2024] usb 1-1.4: Product: UACDemoV1.0[Wed Feb 21 10:33:17 2024] usb 1-1.4: Manufacturer: Jieli Technology[Wed Feb 21 10:33:17 2024] usb 1-1.4: SerialNumber: 1120040804060316[Wed Feb 21 10:33:17 2024] input: Jieli Technology UACDemoV1.0 as /devices/platform/scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb1/1-1/1-1.4/1-1.4:1.2/0003:4C4A:4155.0002/input/input5[Wed Feb 21 10:33:17 2024] hid-generic 0003:4C4A:4155.0002: input,hidraw0: USB HID v1.00 Device [Jieli Technology UACDemoV1.0] on usb-0000:01:00.0-1.4/input2

I have not plugged in any USB devices today, in fact I hadn't even touched the Pi since 08:40 today.

That appears to be a sound card that also has a Human Interface Device (HID) element, hence registering as an input device.
Why it disconnected and reconnected is an interesting question - possibly a power glitch.

I do have the following lines in my crontab which affect the display:

Code:

# turn screen off0 16 * * * sudo sh -c 'echo "1" > /sys/class/backlight/10-0045/bl_power'# turn screen on0 8 * * 1-5 sudo sh -c 'echo "0" > /sys/class/backlight/10-0045/bl_power'

And I have configured the Pimoroni fan shim button to switch on and off the display using the following code:

Code:

#!/usr/bin/env python3import signal, osfrom fanshim import FanShimfanshim = FanShim()def getScreenState():    return os.popen("cat /sys/class/backlight/10-0045/bl_power").read().strip() == "0"def toggle_screen():    if getScreenState():        os.system("""sudo sh -c 'echo "1" > /sys/class/backlight/10-0045/bl_power'""")    else:        os.system("""sudo sh -c 'echo "0" > /sys/class/backlight/10-0045/bl_power'""")@fanshim.on_release()def release_handler(was_held):    toggle_screen()try:    signal.pause()except KeyboardInterrupt:    pass

I'm not sure if this could cause any issues.

Updating the backlight shouldn't have any interaction with the touch controller.

Statistics: Posted by 6by9 — Wed Feb 21, 2024 11:37 am

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