On Wed, Jul 01, 2009 at 09:02:23AM +0300, Catalin Ionescu wrote:
> The Marvell SoC doesn't support isochronous transfers usually needed
> for USB sound cards. USB 2.0 doesn't have isochronous transfer at all
> and thus some devices work and some don't. Being an unreliable data
> transfer method, it is used only for devices that can cope with missing
> chunks of data, thus USB storage devices never use it.
> I have seen myself in the same situation with some exotic devices and
> had to find different solutions. Unfortunately, in my case an USB hub
> never helped.
> So, as long as you know what to use the board for, it will do the job
> properly. But read the SoC errata PDF before!
Thanks. The 50 page errata includes this cryptic statement: "For USB
Isochronous mode support contact a local Marvell Field applications
Engineer or reprentative. Workaround: none" - hence presumably my USB
audio problems. One of the other USB errata presumably explains my 3G
modem problems.
I guess the moral is don't count on USB devices working with a ts7800 until
you've tested them - and I need to find an alternative board.
Errata here:
http://www.marvell.com/files/products/media/88F5182_Functional_Errata.pdf
Andrew
|