On Sat, 14 Nov 2009, Alan Stern wrote:
On Sat, 14 Nov 2009, Theodore Kilgore wrote:
Now, what is happening is that all of the supported cameras work
beautifully when hooked to a machine which is using OHCI. Most of them
also work beautifully when hooked up to a machine which is using UHCI. But
the CIF type 1 cameras fail to work properly if hooked to a machine
running UHCI. They are detected correctly, and apparently are initialized
correctly (I have looked at a bit of dmesg output, usbmon output and such,
by now) but when they are asked to emit a stream across the isochronous
endpoint the stream is not forthcoming.
I have tested now on six machines, as I said. Three of them are OHCI
type machines, and all of the cameras run. Three of them are UHCI type
machines, and the CIF type 1 cameras do not run. Of course, the problem
could be local to the driver code itself. But with a consistent pattern
like that one does begin to wonder.
It could be a matter of insufficient power. Maybe the OHCI controllers
provide more bus current than the UHCI controllers do. Are the failing
cameras bus-powered? (Also, have you tried connecting the cameras to
the UHCI controller through a powered hub?)
Alan,
Thanks. I will try putting a battery in the camera. Indeed, I have been
getting the power over the USB cable. I do not happen to own any USB hub,
neither powered nor unpowered.
Oops, unfortunately the package of batteries on my desk has only one in
it. Only one is needed in these cameras, but when I stick that one in the
camera it starts flashing LO at me. The battery has died of old age, so
this test will need to wait until I can go out shopping for batteries. I
will report about the results when I can.
If that's not the case, perhaps you could post a pair of usbmon traces
for the same camera, showing how it works with one controller but not
with another.
As to the usbmon output, let me know if what is in my previous message to
Oliver Neukom is sufficient.
Theodore Kilgore
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