SUSPEND_MODULES="xhci_hcd"
...and problem vanishes! The above unloads the troublesome kernel module just before system tries to suspend. The module is automatically reloaded when the system resumes, so I had no problem using my ExpressCard after resuming.
@ralph.ronnquist - Thanks for pointing me in the right direction!
]]>I believe the [xhci_pci] module handles USB transport (esp. 3.0), and it is brought in when I plug in a USB stick.
I have an ExpressCard in my laptop that provides two USB 3.0 ports, which I added to my laptop not that long ago. I tried removing the card and, lo and behold, without it suspend works just fine. However, leaving the card out until I want to use it kind of defeats the purpose of a nice flush card such as this, which aims to blend in and become part of the laptop.
It would be good to figure out a way for suspend to work with the ExpressCard in the slot. If anyone knows how to accomplish this, please let me know. If I find a solution, I'll post it here.
]]>Lately, when system is on AC power and I try suspending, it only works sometimes. If I'm on battery power and try suspending, it doesn't work at all--the suspend LED, which looks like a little crescent moon on the T400's LED panel, briefly lights up but the system just keeps going and does not actually suspend.
Last time I upgraded Libreboot was a long time ago, well before installing Devuan. I do apply all of Devuan's security upgrades--is it possible that one of them broke my ability to suspend? I'm using the default kernel (3.16.43-2+deb8u3).
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