Am Montag 05 Mai 2008 11:51:03 schrieb Alan Jenkins:
> Oliver Neukum wrote:
> > Am Samstag 03 Mai 2008 14:36:48 schrieb Alan Jenkins:
> >> I don't think that should count as an "active" device. That's about as
> >> much as I can help. I suggest you ask the linux-usb-users mailing list
> >> - someone referred me there when I was asking about this sort of thing,
> >> and they were pretty responsive and helpful.
> >
> > Any USB device that is not explicitely suspended is active. With the
> > exception of hubs USB devices are not suspended unless their driver
> > and user space via sysfs request it.
>
> But in this case there is no driver. With linux, you have to have a
> driver, e.g. for charging a Blackbery via USB; if it has no driver at
> all then it wouldn't be powered - no? Surely if a device without
This turns out not to be the case.
> drivers isn't considered to require power, then it shouldn't be
> considered to be active? Or is this an illogical quirk of the UHCI
> hardware?
In a way. UHCI needs to do DMA. But many devices crash when suspended.
So the kernel refrains from doing so unless told otherwise.
> Are you suggesting that Sascha and others need to identify all the
> devices without drivers hanging off their USB bus and de-"activate" them
> in sysfs, i.e.
>
> echo "suspend" > power/level
I am suggesting that. Or rather that they use "auto" instead of
"suspend"
> Eww! Are you sure it's that bad? If devices without drivers can't
> expect power, then they can't do anything useful at all and they should
> be de-"activated" automatically :-(.
Too many crash.
Regards
Oliver
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