On Thu, 20 Sep 2012, Ming Lei wrote:

> This patch sets hub device's default autosuspend delay as 0 to
> speedup bus suspend, see comments in code for details.

The explanation in the comments assumes that the only reasons for hubs
to wake up are because of a connect change or a wakeup request from a
child.  This is not correct.

Hubs can also be woken up by the user.  Have you tried running lsusb on
a system with several USB devices attached to the same hub and the
autosuspend delay set to 0?  It's a mess.

I think it would make more sense to set the autosuspend delay to 
something more like 50 or 100 ms.  Maybe even as low as 20.  But 0 
seems too small.

Alan Stern

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