Jonathan Nieder wrote:
Some USB MIDI keyboards fail to operate after a USB autosuspend.
Make that *all* USB MIDI devices with input ports.
This is not a bug in the device, but one of the many bugs introduced with the autosuspend code in http://git.kernel.org/linus/88a8516a2128.
That patch does not handle input at all, i.e., when the driver wants to read from the device, it just doesn't take it out of suspend mode.
A workaround is to disable USB autosuspend for these devices by putting AUTOSUSPEND_USBID_BLACKLIST="0763:2027" (resp. 0763:019b) in /etc/laptop-mode/conf.d/usb-autosuspend.conf. In the spirit of commit 166cb70e97bd ("usb: add USB_QUIRK_RESET_RESUME for M-Audio 88es"), reset the device on resume so this workaround is not needed any more.
It is not feasible to add the IDs of all USB MIDI devices.
I'm working on a fix that adds proper power management for input ports, but this requires the driver to be reorganized a little ...
Regards, Clemens