stamatis is correct.
I have an XPERIA M (C1905) with root access and a LOCKED bootloader.
My testing has shown the XPERIA M supports USB OTG and USB power charging, but not both at the same time
I have tested the following:
• External MicroUSB USB flash and SD card readers are supported directly attached to phone.
• My testing has shown MHL external connections don't work in the XPERIA M with Android 4.1.2 at this time.
MicroUSB port doesn't support power and data at the same time, which is a bad indicator.
• Sony DK10 Media Dock ONLY provides power. It can not provide USB data and power at the same time. Really means it doesn't work.
• Aten 4 port USB switch is supported †
• Targus 7 port USB powered hub is supported
• WD 320GB HDD is supported via a power USB hub
• Logitech USB Unifying mouse supported (sans back key and context menu on mouse) M950,M325 and M905 tested
• Logitech USB Unifying keyboard supported (Esc
- Back and Alt-Menu
- context menu) K800 and K400 keyboards tested
• The supplied microUSB power on the XPERIA M is greater than an XPERIA S, as I can mounted USB flashdrives on the XPERIA M which give a power consumption error on the XPERIA S. Still can't mount a USB powered WD USB HDD directly to the phone. You need a powered hub for that.
- With the XPERIA M connected to an Aten 4 port USB switch it becomes one of four devices that can selectively use all supported USB devices connected in a desktop environment.
For me this feeds a Targus 7 port powered USB hub and a U2410 24" monitor with additional USB ports.
The SD/MMC card reader in the U2410 monitor is available too via the Aten USB switch too.
XPERIA M does seem to support higher powered USB 2.0 devices, but still draws the line before being able to directly support the likes of WDC USB 2.0 Hard Disk Drives.