Offenders

Originally Published Dec 20, 2011 @ 10:19. Updated frequently as we learn more about this device and how it interfaces with Linux.

This first section is geared towards Linux distributions that use the rpm package manager. Either way, it should give you an idea of how to accomplish the same with any other distribution.

This phone and many others are doing away with the mass storage device method of connecting to a pc for transferring files. MTP is the new method, but each vendor and device id must be added to the mtp library before the device is recognized. In Fedora, this is relatively easy to do. Pull down the source rpm using yumdownloader. Install yumdownloader if you don’t have it already.

# yumdownloader –source libmtp
# rpm -ivh libmtp*.src.rpm
# cd ~/rpmbuild/SOURCES

RedHat has already created a diff to append a bunch of new devices to the code. We just need to add ours to the list. The US model of the Samsung Galaxy Nexus is 04e8:685c. You can verify yours by typing lsusb. There are many ways to do this but this should give you an idea of how it works. Add the following lines to the diff file. I’d add it with the other Samsung devices, then find the diff hunk above that section and increment 5 to the destination file range (since we’re adding five lines to the total patch, not just the two we’re inserting). In my case this works..

Edit device-db.patch.

//@@ -248,13 +254,28 @@     <– old
@@ -248,13 +254,33 @@

Then append this to the bottom of the Samsung section.

+ // From: Ryan Sweat <rsweat@gmail.com>
+ { “Samsung”, 0x04e8, “Samsung Galaxy Nexus”, 0x685c, DEVICE_FLAG_BROKEN_MTPGETOBJPROPLIST_ALL },

Save the file, then recompile the rpm.

# cd ../SPECS
# rpmbuild -bb libmtp.spec

If successful, it should build the packages with US Samsung Galaxy Nexus device support. Remove the current rpms and install the new versions.

# rpm -e libmtp libmtp-hal libmtp-devel –nodeps
# yum localinstall ~/rpmbuild/RPMS/x86_64/libmtp-*.x86_64.rpm ~/rpmbuild/RPMS/x86_64/libmtp-hal-*.x86_64.rpm ~/rpmbuild/RPMS/x86_64/libmtp-devel-*.x86_64.rpm

That should be enough for apps like Amarok to detect and use the device. If you want to mount the device’s filesystem, you’ll need mtpfs as well. Here’s how to install mtpfs. It has a few dependencies. The configure process will complain if others are needed.

# sudo yum install fuse fuse-devel libmad libmad-devel libid3tag-devel libid3tag

# wget http://www.adebenham.com/debian/mtpfs-1.0.tar.gz
# tar xvzf mtpfs-1.0.tar.gz
# cd mtpfs-1.0
# ./configure && make && sudo make install

Edit /etc/fuse.conf as root and append or uncomment this line.
user_allow_other

Create a mountpoint, owned by your regular userid.
# sudo mkdir /mnt/nexus
# sudo chown user:user /mnt/nexus

Mount the device.
# mtpfs -o allow_other /mnt/nexus

To unmount it.
# fusermount -u /mnt/nexus

** EDIT 20111223 **
To make this device auto mount when connected, edit /lib/udev/rules.d/60-libmtp.rules or create it if it doesn’t already exist.  Find or add the entry for the Samsung Galaxy Nexus and the two ACTION lines beneath it.

# Samsung Galaxy Nexus
ATTR{idVendor}==”04e8″, ATTR{idProduct}==”685c”, SYMLINK+=”libmtp-%k”, ENV{ID_MTP_DEVICE}=”1″, ENV{ID_MEDIA_PLAYER}=”1″
ACTION==”add”, RUN+=”/usr/local/bin/mtpfs -o allow_other /mnt/nexus”
ACTION==”remove”, RUN+=”fusermount -u /mnt/nexus”

I’ve found that if the screen is unlocked when connected, it mounts at what would normally be the external storage (sd card). Otherwise, it mounts where only the Playlist directory is viewable or accessible. This is likely a security feature. I’m surprised it’s able to mount at all with the phone locked or turned off, as a commenter below has mentioned.

** End edit 20111223 **

** Edit 20111228 **

Interestingly, the Product ID changes when this device is put into USB debugging mode from PID=685c to PID=6860. The latter is recognized by libmtp as a Samsung GT-P7510/Galaxy Tab 10.1/S2 which, according to the patch, was “Reported by anonymous sourceforge user”. It mounts successfully with this PID with flags DEVICE_FLAG_UNLOAD_DRIVER and DEVICE_FLAG_LONG_TIMEOUT, even though the device isn’t an Galaxy Tablet. I’m curious as to how two Samsung devices can have identical USB PIDs, and if it’s standard behaviour for a product id to change when put in usb debugging mode.

** End edit 20111228 **

** Update 20120111 **

A commenter, gofasterplease, discovered an issue with writing certain multimedia files to the mounted filesystem. I started testing myself after reading his comment and I was also experiencing this as well.

What I did notice is that certain file extensions seem to be blocked from being written to certain locations on the filesystem. The source file is opened O_RDONLY, the destination file descriptor is opened, O_WRONLY|O_CREAT|O_EXCL, written to, then closed and exits with status 0, meaning successful, at least from the standpoint of the application performing the write. I tested 30 well known audio types, including proprietary ones, and mp3 is the only one I could find that exhibits this behaviour. I initially thought they were blocking the proprietary mp3 format for licensing reasons, but that’s not possible since I’ve uploaded 19k+ mp3s to Google Music and constantly steam them throughout the day (which caches the mp3s locally).

After further testing, I finally determined files ending in .mp3 are automatically moved to the Music/ directory. I’m ashamed it took me an hour or so of testing to figure this out, but this activity is difficult to detect when it’s done on the android side after the file is successfully written. Hope this helps explain some odd behavior when copying files around.

** End Update 20120111 **