USB camera compatibility question

[Barry Bouwsma]

[IPv6-only address etc etc; drop for replies, I read the archives periodically]

Weeks ago, Bernd Walter <ticso at cicely12.cicely.de> wrote...

> On Fri, Nov 21, 2003 at 02:48:46PM -0500, Barney Wolff wrote:
> > On Fri, Nov 21, 2003 at 01:43:13AM +0100, Barry Bouwsma wrote:
> > Yes, because so far the images snarfed with my hacks are okay for the
> > first 4096 bytes, thereafter failing to match the perfect images I can
> 
> > The "junk at byte 4097" symptom matches what I get with a Sony F707
> > on -current using the OHCI usb controller.  I believe it's a bug in
> > the ohci driver but don't know more than that.

> You want ohci.c rev 1.139

I'll keep that in mind -- at present, I've had successful OHCI operation
with a usb KLM with ohci.c rev 1.39.2.9, uhci.c rev 1.40.2.11, and umass.c
either 1.11.2.21 or based on that patched from current -- my source is a
mess, ugh.

However, with the above kernel modules that worked fine with an OHCI card,
when I connect the camera to a UHCI card, I confirm my earlier observation
that data transfer rates from the camera are only ~60kB/sec -- more than
5 times slower than with the OHCI card.  Enough for me to go and drink a
Maß of coffee while I copy a good-sized detailed porn^H^H^Hicture, which
previously was not necessary.

The other kernel module(s) I have tried, perhaps when I experienced the
corruption following byte 4096, have ohci.c rev 1.132, and uhci.c rev
1.145, but I can't remember what transfer rates I was seeing with that
and UHCI.

I'm quite sure I see no such limit to a conventional UHCI-connected disk --
in fact, at the moment I'm getting ten times the max rate the camera gave
me (0,55 - 0,87MB/sec) with normal writes, not pushing any limits.

Apart from the card in use, the setup of the camera (to hub to card) is
identical between the UHCI 60kB/sec and OHCI 300-500kB/sec reads from the
MSDOS filesystem.  Just wondering if this difference in speed is a known
issue (or was previously an issue).


One of these days I'll get around to updating the kernel modules and seeing
if the speed difference still is observed.  One of these days...


thanks
Barry Bouwsma