This LTE modem (M.2 card) has a bug in its power management:
there is some kind of race condition for U3 wake-up between the host and
the device. The modem firmware sometimes crashes/locks when both events
happen at the same time and the modem fully drops off the USB bus (and
sometimes re-enumerates, sometimes just gets stuck until the next
reboot).
Tested with the modem wired to the XHCI controller on an AMD 3015Ce
platform. Without the patch, the modem dropped of the USB bus 5 times in
3 days. With the quirk, it stayed connected for a week while the
'runtime_suspended_time' counter incremented as excepted.
Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
Link: https://lore.kernel.org/r/20210319124802.2315195-1-vpalatin@chromium.org
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
0bd860493f