Re: [linux-usb-devel] Error -71 on device descriptor read/all

[Alan Stern <stern@rowland.harvard.edu>]

On Tue, 19 Jun 2007, Paul Walmsley wrote:

> On Tue, 19 Jun 2007, Oliver Neukum wrote:
> 
> > Am Dienstag, 19. Juni 2007 schrieb Chuck Ebbert:
> >
> >> Try disabling CONFIG_USB_SUSPEND
> >>
> >> [usb developers: what are the drawbacks of doing this?]
> >
> > Increased power consumption.
> 
> speaking of CONFIG_USB_SUSPEND, I've encountered at least one device -- a 
> Canon EOS 5D camera -- that, after the bus suspends, must be powercycled 
> in order to return the camera's interrupt endpoints to a functional state. 
> How are these types of problems handled, currently?  Is this something for 
> a blacklist?

There are a few possible approaches.  One is indeed a blacklist, to 
prevent the camera from automatically being suspended.  Another is to 
prevent it by changing a device parameter in sysfs.

Note that neither of these will help if you do a suspend-to-RAM.  That 
suspends everything.

Alan Stern

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