Ubuntu 20.04 usb not working (when running on battery)

Question

I updated to ubuntu 20.04 a couple of days back, and I noticed that it is not picking up USB disks when running on battery. When I plug-in power, the OS immediately picks up the USB drive.

I am running a Thinkpad T495 with AMD Ryzen 5 PRO 3500U w/ Radeon Vega Mobile Gfx. Kernel is,

Linux ThinkPad-T495 5.4.0-26-generic #30-Ubuntu SMP Mon Apr 20 16:58:30 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Any help on this is much appreciated.

UPDATE: The same applies to USB keyboard. It would only be detected while running on power and after connecting, I can disconnect A/C power and continue without a problem.

PS:

I am also having a similar issue regarding boot up, where the OS wouldn't boot up on battery.

Ubuntu 18.04 and 20.04 stuck on gnome startup (on battery only)

Best

Solution

To assist others (ignoring the whining).

On the T495 this is indeed down to TLP, disabling TLP and rebooting caused USB devices to work on battery alone.

For me the fix was to run lspci and find the AMD USB controllers.

06:00.3 USB controller: Advanced Micro Devices, Inc. [AMD] Raven USB 3.1
06:00.4 USB controller: Advanced Micro Devices, Inc. [AMD] Raven USB 3.1

Then add them to the RUNTIME_PM_BLACKLIST in /etc/tlp.conf

RUNTIME_PM_BLACKLIST="06:00.3 06:00.4"

Reboot - USB works on battery whilst TLP is still functional. Therefore yes my original post was right, it does seem to be an AMD thing.

Comments

[n1r44]

I think this was due to TLP. When I removed TLP things were switched back to normal.