Hello, I'm an owner of a Jiayu G3S phone, an MTK6589 (1.2GHz quad-core) device.
Trying to make it work with libmtp, I seen that the support to its VID/PID has been disabled with a comment saying
This had to be commented out - the same VID+PID is used also for other modes than MTP, so we need to let mtp-detect do its job on this device instead of adding it to the database.
I added my own rules to udev and Gnome works quite good, but Rhythmbox does not, because it checks against libmtp device list, so there is no point to use MTP at all to me (I'd use it just to sync my music with a proper playlist support).
So here I am to report all VID/PID combination for this device (and likely all MTK6589/MTK6577 devices, at least from Jiayu):
UMS : 0bb4:0001 CDR : 0bb4:0001 UMS+ADB: 0bb4:0c03 CDR+ADB: 0bb4:0c03 MTP : 0bb4:2008 MTP+ADB: 0bb4:0c02 PTP : 0bb4:200b PTP+ADB: 0bb4:200c
I hope this will be enough to add support in libmtp for these devices. Please consider to not disable them because there could be other buggy devices reporting the very same VID/PID for different modes: IMHO it is unfair penalize good working devices to protect bad working ones (i.e. one should blacklist his buggy device, not whitelist the good one).