Re: Problem on au1100 USB device support

[Rodolfo Giometti <giometti@linux.it>]

On Tue, Oct 10, 2006 at 03:33:45PM -0400, Dan Malek wrote:
> 
> Many people, including myself, have spent way too many
> hours trying to make this device interface work.  There
> are some errata associated with it, along with some challenging
> design problems.  I have only been able to make it work
> in one instance, with a highly custom RTLinux driver,
> properly matched FIFOs and DMA, and running TCP/IP
> over the link.  It wasn't 100% reliable, but the TCP retries
> made it appear that way to the application (with tolerable
> delays).

May I have your setup sequence? At least I'd like to se some bus
activity...

> The device interface just requires too much babysitting
> by the CPU to function, and the Linux interrupts
> have too much latency to guarantee the CPU can do
> what is necessary in a timely fashion.  The same is
> true of not using DMA.  If you choose not to use the
> DMA for data transfer, the CPU just can't respond
> quickly enough to the interface state changes
> unless you just spend all of your time polling the
> interface.

Ok, but as first step I'd like having some functionality with FIFOs.

> IMHO, I wouldn't waste much time on this, but
> Good Luck if you choose to do so :-)

Thanks a lot!

Rodolfo

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