Re: USB drive light does not turn off after "safely removing"

["Mikkel L. Ellertson" <mikkel@xxxxxxxxxxxxxxxx>]

Tim wrote:
> On Fri, 2008-04-11 at 09:43 -0500, Mikkel L. Ellertson wrote:
> > As far as I know, Linux does not shut down the power to the USB 
> > socket when you "safely remove" a drive. It is something that could 
> > be added, though it will not be simple. 
>
> I don't think that you could do that.  Even if you could, how would it
> then tell if something was plugged back in again?  It couldn't.
You have to turn the power back on. But how long do you wait? I 
don't know enough about USB to know if they can detect when the 
device is removed if it is powered down. It may also be possible to 
tell a device to shut down.

As far as turning the power off, I know the kernel can do it. There 
were a couple of kernels that were enforcing the power limits on USB 
sockets, but it was causing too many problems for users. Each device 
is supposed to report its maximum power draw, and each hub is 
supposed to report how much each port can draw, as well as the total 
for the hub. If you plug in a device that draws more then the port 
can handle, or enough devices that you exceed the hub total, the 
port is supposed to shut down.

Mikkel
--

  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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