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 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
