[Bug] Backlight issue with Split Keyboards

[iraytrace]

Split keyboard only turns backlight per-key LEDs of on half that is directly connected to the computer when host system sleeps

Describe the Bug

When the system sleeps, the half of the split keyboard not directly connected to the computer leaves the backlights on.

Quefrency keyboard Rev3 with latest QMK. Host computer sleeps/powers down and the connected half of the keyboard turns off the per-key backlight LEDs. On the other half of the keyboard the backlight LEDs stay lit.

System Information

• Keyboard:
  QueFrency Rev3
  • Revision (if applicable):
• Operating system: Windows
• AVR GCC version: avr-gcc.exe (GCC) 8.4.0
• ARM GCC version:
• QMK Firmware version: 0.14.23
• Any keyboard related software installed?
  • [X] AutoHotKey
  • [ ] Karabiner
  • [ ] Other:

Additional Context

[drashna]

Can confirm that this is happening. No idea why, though.

[mb1986]

Can confirm the same behavior for Keebio Levinson rev3.

[moroz-slavomir]

I have the same problem with kyria + elite-c.

[moroz-slavomir]

I think this is related to the fact that split keyboard communication is part of matrix_scan(), and how suspend is handled on avr + lufa platform.

When in suspend and NO_USB_STARTUP_CHECK is not defined, the board

• invokes suspend_power_down() that sets rgb suspend state on master half.
• waits for the remote device to power up. Until then, it waits in loop. This behaviour blocks the keyboard_task() from being invoked, which would then start the matrix_scan().
  • if matrix_scan() is not invoked, the rgb suspend state won't get transferred to the slave.

If your remote device is sleeping instead of shutdown and can be awoken by USB, then the loop attempts to wait for suspend_wakeup_condition(), which internally also invokes matrix_scan() that synchronizes rgb config and rgb suspend state.

In my case, if I put my PC to sleep, both halves turn off their rgb lights, but when I shutdown the computer, the slave won't. When I added an extra execution of matrix_scan() on suspend for split keyboards, the issue disappeared for my keyboard and both halves turned off the rgb.

[stephaje]

Also seeing this problem on the keebio/iris/rev6.