I have two cardbus USB2 cards, one using an ALI chipset and one using an NEC chipset.
They both exhibit a problem while attempting to write bulk data.
... the crux of it is a usb_stor_bulk_transfer_sglist will fail by not
triggering an interrupt.
Almost any recent EHCI has an "I/O watchdog timer", specifically because certain VIA EHCI hardware seems sometimes to forget IRQs. (Never seen with any other EHCI silicion, at least by me.) So lost IRQs doesn't seem a likely explanation to me; EHCI could run entirely by timer.
If I insert the card, then remove the ehci-hcd module then the card drops back to USB1.1 and it works perfectly with the usb-ohci driver (Kernel 2.4 but same diff under latest 2.6-bk).
Does ohci use dma ?
Yes. But much less than EHCI ... :)
Your symptoms don't make much sense to me, except as an issue with your CardBus bridge. Since you say Windows has similar problems, maybe the answer is just not to use that combination of hardware.
- Dave
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