dmesg shows these extra lines when device plugged in:
umass0: <\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^?\M^? HUAWEI Mobile, class 0/0, rev 1.10/0.00, addr 2> on uhub1
cd1 at umass-sim0 bus 0 target 0 lun 0 cd1: <HUAWEI Mass Storage 2.31> Removable CD-ROM SCSI-2 device cd1: 1.000MB/s transfers cd1: Attempt to query device size failed: NOT READY, Medium not present NOTE_1: dmesg is the same with or without my patch. NOTE_2: I think the "Medium not present" is the empty MicroSD slot
