Repeating or dropped keystrokes with Kali, Raspberry Pi 4, and a TP-Link wifi dongle

[jymm]

Hello all,

First my apologies if this topic has been discussed. I did try searching but came up empty.

I have a Kali 2019/4 ARM installation for a Raspberry PI 4 that uses a TP-Link TL-WN722N WiFi dongle. When it's all up and running, keystrokes are dropped or repeat. Originally I had a Logitech wireless keyboard/mouse and blamed those devices, but I replaced them with a plain-vanilla wired keyboard and mouse only to find that the problem continued. I removed the TP-Link WiFi dongle and the problem cleared up instantly. Upon plugging the WiFi dongle back in, the problem of dropped/repeating keystrokes returned immediately. I tested the USB ports themselves, exchanging the dongle to and from a USB 3 port and doing the same with the keyboard and mouse - none of which altered the behavior. I also used a USB extension cable to move the TP-Link away from the PI but that did nothing to alleviate the problem. Other equipment includes a plastic case and a Pimoroni FanShim but I don't think that creates or adds to the problem. Any point in the right direction would be helpful. Thanks in advance for your time!

[steev]

What kernel version are you on? I've seen this issue crop up occasionally on the rpi4 and it's due to the usb bus. Older kernels definitely had issues, but I hadn't seen it on the 4.19.93 kernel. If you do continue to have the issue, one possible workaround is to lower the amount of ram available to the device, by putting something like

total_mem=3072 in your config.txt file under the [pi4] block

Do make sure you're up to date though, I thought this problem was fixed in newer kernels.