USB in client mode

[ABATAPA]

Hello!
Can be USB used in "client" mode,  for example, with g_file_storage.ko, to emulate a USB mass storage device?

[Rabeeh Khoury]

The Kirkwood SoC supports being device mode, but -
1. Since the hardware is configured to be host mode; it drives the USB power - so if you plug the connector to a host PC then there will be a short circuit (you need somehow to open the box, and disconnect the power driving).
2. You need to use Marvell LSP 2.6.22.18, which supports device mode (the open port kernel 2.6.30-X doesn't support device mode yet).
3. Set in uboot the env variable 'usb0Mode' to 'device' instead of 'host'.

[ABATAPA]

The Kirkwood SoC supports being device mode...

Thank you! Basic - this is supported in hardware.
So, perhaps to use the device as a bootable media is write-protected or copy-on-write (to protect the data from changes), etc.

[Rabeeh Khoury]

well, i think software wise it's doable.
The only thing I would be afraid of giving such a method to newbies and they might accidently not tweak the Vbus voltage that the plug provides (since it's default is host) and might do some short circuit between a plug and a host PC.

[dieterk]

AFAIK there is a bus power load switch on the plug - at least at my hardware revision.
So it shouldn't be so hard to disable bus power if driver loads in device mode?

Dieter

well, i think software wise it's doable.
The only thing I would be afraid of giving such a method to newbies and they might accidently not tweak the Vbus voltage that the plug provides (since it's default is host) and might do some short circuit between a plug and a host PC.

[boerner]

I can see one possible benefit of this (if it can be made to work) as a way to network a very popular media player device, the Western Digital WD TV Media player.

http://www.wdc.com/en/products/products.asp?driveid=572

the device itself is fairly open and a lot of homebrew apps and firmware have appeared:

http://wdtvforum.com/main/

If you can access the Sheevaplug as a NAS to put files on local storage, and then change modes so that it appears as mass storage to the WD TV, presto, instant networked device.