Re: [linux-usb-devel] Re: "sr: unaligned transfer" in 2.5.2-pre1

Jens Axboe
2002-01-01T17:41:03Z

On Mon, Dec 31 2001, Matthew Dharm wrote:
> Jens --
>
> Thanks for the info. It may have been discussed 'here' (tho, this is
> crosposted to two different lists), but I've been focused on 2.4 bugs (one
> more left!) and hadn't seen this item.

oh sorry, 'here' means linux-kernel to me :-)

> I think for the first 2.5 kernels, we'll o with your 'vaddr' line, but I
> think that being able to set highmem_io is a worthwhile thing. Which leads
> me to two questions:

indeed

> (1) Do the USB HCDs support highmem? I seem to recall they do, but I'm not
> certain.

most likely, I don't know though. I would imagine they support full
32-bit dma.

> (2) How do I pass a highmem address to the HCDs? The URB structures we use
> don't seem particularly well-suited for this.

you need to use the pci dma mapping interface, see
Documentation/DMA-mapping.txt

--
Jens Axboe