Re: USB da(4) quirks deprecated

On Sat, 13 Sep 2003, John-Mark Gurney wrote:
> Andrew Thompson wrote this message on Sat, Sep 13, 2003 at 16:33 +1200:
> > I have just got around to trying this pen-drive again and have been
> > trying tracking down data corruptions.  If I mount the drive, write a
> > file, umount/mount again the file is different.
> >
> > Using cmp I have found that there are consistent blocks of nulls in the
> > written file where data should be. The block is always 0xfff bytes long
> > and starts at 0x3000.  I have tried many files and the offsets are
> > always the same. All the other data in the file is correct and at the
> > right location.
> >
> > 0x3000 -> 0x3fff
> > 0x7000 -> 0x7fff
> > 0xb000 -> 0xbfff
> > 0xf000 -> 0xffff
> > 0x13000 -> 0x13fff
> > ... and so on until the end of the file ...
> >
> > Any suggestions?

This almost certainly has nothing to do with quirks.

> Is this on an ohci controller?
>
> I'm trying to track down mbr's problem also that appears to do the
> same thing.  Have you tried doing an fstat before umounting the fs?

I think you mean fsync?

> (There is a bug in msdosfs that doesn't sync the disk before unmount
> completes.)
>
> This is wierd in that it's the second page of the second transfer.
> The ohci can do up to 8k transfers in one TD, and then chain the TD's
> together if a larger block sized is used.

Maybe you can provide him a patch that limits transfers to a single page
as multi-page descriptors might be broken on his controller.

-Nate