On Sat, 14 Nov 2009, Alan Stern wrote:
On Sat, 14 Nov 2009, Theodore Kilgore wrote:
On Sat, 14 Nov 2009, Alan Stern wrote:
On Sat, 14 Nov 2009, Theodore Kilgore wrote:
First the log where it fails, done on a Dell C600 Inspiron laptop (I have
tested on a couple of much newer machines, too, in case you think this one
is too old, but with no different outcome):
Now similar lines from the log for the same camera, on a machine where the
camera is working properly:
The first log shows that the camera was sending packets okay; the
packets were just empty. So it's not like the camera was failing to
work at all. The second log was the same as the first except that the
packets were not empty; they contained data.
Indeed, this is suggestive of something like not having enough power.
Alan Stern
Indeed, indeed. Except that being able to find a good AAA battery in the
house and putting it in the camera did not help the camera to stream, at
all. So it is something else.
Well, then I'm stumped.
Alan, I have known you for a long time. That's a new one :)
There appear to be two possibilities. One is that the camera really is
sending nonempty data packets, but for some reason uhci-hcd doesn't get
the data. The only way to verify this would be to use a USB bus
analyzer.
How much does one of those things cost? Perhaps I should have one. Perhaps
I could try to argue my boss into helping pay for it, if I am lucky...
The other is that the camera really is sending empty data packets.
Then one has to figure out why the camera behaves differently in the
two environments; presumably only the manufacturers have enough
information to make that determination.
They do not share that information with us, of course. However, the same
camera does work nicely when connected to any one of three OHCI-based
machines on which it was tested, running the same driver code. No problems
at all. And it fails to work on three UHCI-based machines. It also must
have worked on Windows, because there were some logs made over there. And
I suspect that the Windows machine had in it either a VIA or an Intel
chipset on the board, too...
Perhaps I should mention some details about the three UHCI-based machines:
-- the old Dell laptop, which has PII4 Intel stuff inside
-- eeePC 1000
-- AMD Sempron 2600 system on a VIA-based board, K8M800 host bridge, VIA
82xxxxx UHCI USB 1.1 controller.
The camera is also a USB 1.1 device.
Theodore Kilgore
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