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?)
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.
Alan Stern
Alan,
Update. I found a good battery. But there is no good result. It does not
help the situation.
Theodore Kilgore
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