USB-attached mtp Devices Work Differently With ext4, exFAT, and NTFS

[martinjdz]

I recently did a clean install of Kubuntu Version 22.04 KDE (UEFI mode) on a brand new desktop PC. I soon began having difficulty copying audio files from an ext4 partition to either of two different USB-attached audio players. (They are similar to the Sansa Fuse kind of device.) Both players support the mtp protocol. They are not Android devices.

The problem is that the connection to the player fails without warning after a couple of minutes----even while it is in the process of copying multiple files. To resume copying, I must unplug the player, restart the player, and plug it back in.

My previous computer had Kubuntu 20.04 (MBR mode) with a similar set of KDE applications. However, I was storing audio files on an NTFS partition (not ext4). There appeared to be no problem copying files from the NTFS drive to the media player. (At least, there was no problem until the NTFS partition began to get corrupted after about 2 years. But that's a different problem and a different story.)

Unable to copy files reliably from my new PC to the audio players, I took the following steps.

1. I took an old external drive and reformatted it as exFAT.
2. I copied my audio files from the ext4 partiton to the exFAT drive.
3. I then copied the audio files from the exFAT drive to the audio player.

This seemed to put an end to the connection loss problem. I believe that I was loosing the USB connection because the player didn't like something about the ext4 partition or the ext4 storage format. The main problem, I believe, is NOT lack of support for the mtp standard; it is incompatibility between different disk formats.

[oshunluvr]

Never heard of that but you never know. Seems odd to me because normally the file system on one device has nothing to do with the other. I'd be more suspicious of the MTP protocol having an issue with EXT4.

Did you look in your logs or at least at dmesg output when this occurs? There's very little actual information here that might lead to a solution or a reason.

Welcome to the forum.

[martinjdz]

I'm not sure what dmesg is or how to access that info.

I opened up the KSystem Log utility, looked into Journald Log (mtp-probe), and examined the various entries. It said, over and over again:

Device [##] is not an mtp device

There are no kdeconnect log messages. (KDE Connect does not recognize the attached media player.)


In the System Log (all messages), I see many instances of each of these messages:

kf.kiod.kmtpd.: Unknown connection error

Unaligned transfer

Buffer I/O error on dev sr0, logical block 5, async page read

blk_update_request: I/O error, dev sr0, sector 0 op 0x0 READ) flags 0x80700 phys_seg 4 prio class 0