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Environment used: - linux kernel 7.20.rc-4-dirty - qemu-system-x86_64 version 11.0.50. The arguments used were(This passes the keyboard through to qemu): -kernel "$BZIMAGE" -machine "q35" -cpu max -vga std -display gtk -device qemu-xhci,id=xhci -usb -device usb-host,bus=xhci.0,vendorid=0x046d,productid=0xc31d -initrd "$INITRAMFS_CPIO" -m 1G -smp 4 -no-reboot -virtfs "local,id=lkmpg,path=$PROJECT_ROOT,security_model=none,mount_tag=lkmpg" -append "nokaslr" (this is a slightly modified version of the qemu environment specified at the start of the Linux Kernel Module Programming Guide) - Qemu itself runs in a distrobox container running an Ubuntu 26.04 LTS - My host is Fedora Kinoite 43 with kernel version 6.17.12-300.fc43.x86_64(where I first noticed the issue) - The keyboard's vendorId : productId -> 046d:c31d Steps for reproduction: - Run hexdump -v on the appropriate /dev/input/event entry - Press the volume up button on the keyboard, slowly - Given enough time between key presses all presses cause a change in output with corresponding press/release entries - Rapidly press the volume up button on the keyboard - Notice that output either: 1. Doesn't change at all. 2. or after some time, it sort of gets flushed and you see a bunch of entries output all together. Expected Behaviour: Each button press/release should correspond to an event. Some Notes and Logs: - I concluded that this isn't likely to be a hardware issue as the expected behaviour was shown on Windows 11. - I noticed this issue first in kernel 6.12.12, and later I tested it in 7.20.rc-4-dirty and discovered that the issue still persists. - I hacked on the kernel in an attempt to figure out the problem myself, adding pr_info statements dumping state in evdev_read, input_event_dispose and hid_irq_in and saw the following(linked is my raw dmesg output without my changes, output grepping my pr_info statements and my .config. I have delimited the 3 sections by using a bunch of '=' characters): https://pastebin.com/59FsWsvq It seems to me that there are a lot of unnecessary SYN_REPORT calls with a disposition that triggers a flush of the device's inputs such as: [ 110.907511] input: input_event_dispose for device Logitech USB Keyboard Consumer Control of type: 0 code: 0 value: 0 dev->num_vals: 1 dev->max_vals: 11 [ 110.907543] input: input_event_dispose for device Logitech USB Keyboard System Control of type: 0 code: 0 value: 0 dev->num_vals: 1 dev->max_vals: 10 [ 111.035339] hid_irq_in device: 1133:49949 status: 0 [ 111.035412] input: input_event_dispose for device Logitech USB Keyboard Consumer Control of type: 0 code: 0 value: 0 dev->num_vals: 1 dev->max_vals: 11 [ 111.035431] input: input_event_dispose for device Logitech USB Keyboard System Control of type: 0 code: 0 value: 0 dev->num_vals: 1 dev->max_vals: 10 ...but I couldn't get any further than that. - Also, I noticed that the polling rate for consumer/system control is set to 255 ms whereas the main keyboard is set to 10 ms(I got this from the bInterval value while debugging). Would appreciate guidance on this.