On Nov 8, 2008, at 4:53 AM, Hans Petter Selasky wrote:
On Saturday 08 November 2008, Alexander Motin wrote:
Hans Petter Selasky wrote:
http://perforce.freebsd.org/chv.cgi?CH=152649
Change 152649 by [EMAIL PROTECTED] on 2008/11/08 09:09:50
Fix a serious BUSDMA bug: The initial virtual page offset is
not retained on the bounce pages, which is what the EHCI and
the OHCI expects.
I'm sorry, but are you sure with this? If bounce page will have the
same
page offset as original data, then how bus_dma_tag_create()'s
alignment
parameter expected to work? What if data are misaligned, but hardware
require alignment?
Hi,
I'm not saying that my patch is fully correct for all cases, but at
least it
solves the USB case. USB uses an alignment of 1-byte for data.
Another way to look at it is that USB (at least EHCI) uses page-aligned
data and that for the first descriptor you can optionally add an offset
within the page. Effectively this gives you 1-byte alignment, but it
comes with the restriction that on crossing the page boundary, all data
comes from offset 0 on subsequent pages.
--
Marcel Moolenaar
[EMAIL PROTECTED]
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