Quoting Victoria W. <[EMAIL PROTECTED]>: > If I try to use two cam-sevices (pwc oder others) at the same time, only > one of them is working. > Each time, I try to access the other one, I get: > > hub.c: already running port 1 disabled by hub (EMI?) > > I have tried it with several different uhci-hardware - even if I use an > external hub. It's everytime the same. (it does not depend on usb-uhci.o > or uhci.o) > Only with an usb-ohci.o-hardware it works.
I tried running several cameras off of ONE controller (either OHCI or
UHCI), and it didn't work well. Not with Philips cameras though. I saw
occasional "freezes" of the picture that required restart of the v4l
viewer or replugging the camera (probably not.)
This is likely because my cameras *always* requested full Isoc bandwidth
(transfers of 1022 bytes), and that is entire USB frame. Do it often
enough - and cameras love that (for FPS's sake) - and one camera easily
consumes entire bandwidth of the USB bus (which is not that much to begin
with).
This is remedied by using separate USB controllers, one per camera. Not
ports - controllers!
Many computers today (desktops at very least) come with two controllers,
and I use PCI cards that have 4 controllers on each card; I installed two
such cards into one of my boxes, and that makes 9 (8+1) USB HCs. I need
all the bandwidth I can get for the work that I do on that box.
Dmitri
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