Pretty much for my entire career in Linux USB (eight years now?), we’ve been complaining about how USB device power management just sucks. We enable auto-suspend for a USB device driver, and find dozens of different USB devices that simply disconnect from the bus when auto-suspend is enabled.
For years, we’ve blamed those devices for being cheap, crappy, and broken. We talked about blacklists in the kernel, and ripped those out when they got too big. We’ve talked about whitelists in userspace, but not many distros have time to cultivate such lists.
See Sarah Sharp’s full Google+ post or read about the resulting patch on the Linux-USB mailing list post.
