Date: Fri, 05 Apr 2002 14:48:33 -0800 From: Darryl Okahata <darrylo@soco.agilent.com> To: Tomas Pluskal <plusik@pohoda.cz> Cc: freebsd-hardware@FreeBSD.ORG Subject: Re: umass0: BBB reset failed, TIMEOUT Message-ID: <200204052248.OAA25860@mina.soco.agilent.com> In-Reply-To: Your message of "Fri, 05 Apr 2002 23:37:32 %2B0200." <20020405232437.D253-100000@s096-n062.tele2.cz>
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> I am using uhci, according to usbdevs:
> addr 1: UHCI root hub, VIA
Hmmm. Is this an older motherboard? Older VIA chipsets supposedly
had buggy USB implementations, although some people say that this isn't
true, and that the problems were due to the ports not being able to
supply enough power (and that adding a USB hub would fix the problem).
Unfortunately, I don't know which motherboards supposedly have this
problem. I am, however, using a somewhat recent ASUS A7M266 motherboard
with a VIA 83C572 USB controller, and I have no problems.
Is the camera powered by the USB bus, or does it have it's own
power supply? I ask because two possibilities come to mind:
* If the camera is drawing power from the USB bus, it may be drawing too
much power. The absolute (not average) maximum power that a USB
device can draw is 500mA, which isn't much.
[ I ran into this problem with my USB hard disk, which would draw too
much power (surge current) and intermittently fail when connected to
the USB port. ]
* If the camera does draw power, the camera's electronics may not have
been fully initialized (powered up) when USB communications starts to
occur. This should not be happening, but there may be a bug
somewhere.
[ This should be testable by having FreeBSD delay USB communications
when a device is attached, but I do not know how to do this. ]
--
Darryl Okahata
darrylo@soco.agilent.com
DISCLAIMER: this message is the author's personal opinion and does not
constitute the support, opinion, or policy of Agilent Technologies, or
of the little green men that have been following him all day.
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