2005/12/16, Alan Stern <[EMAIL PROTECTED]>:
> On Fri, 16 Dec 2005, Franck wrote:
> > OK, I think I get the main idea of suspend/resume process for usb. But
> > now, I don't see the purpose of hcd->bus_suspend method. What is it
> > supposed to do since all of its children must be suspended (meaning
> > that the bus is already suspended)
>
> No, that's not what it means. Suspending all the devices attached to a
> bus is different from suspending the bus itself.
>
Well stopping any activity on the bus (that's what happen when
suspending all devices from the bus) sounds to me like suspending the
bus...
> > before executing this method ? I
> > guess I don't see the purpose since I have a host controller with only
> > one port, no root hub.
>
> By definition every host controller, including yours, has a root hub.
> That one port is the root hub's downstream port.
>
> The point of a bus suspend is that the host controller can save power by
> turning off the circuitry that drives the USB bus. For example, often
> there's a 48 MHz clock that isn't needed when the bus is suspended.
>
ok so bus_suspend is actually used to suspend root hub or hcd
circuitry related to bus activity ? If so I can't do anything useful
here with my hardware.
> > BTW, I notice a regression. I can not use anymore my usb stick with an
> > embedded hub, I got the following error message:
> > """
> > usb 1-1: new full speed USB device using vusb-hcd and address 5
> > usb 1-1: can't connect bus-powered hub to this port
> > hub 1-0:1.0: state 5 ports 1 chg 0000 evt 0002
>
> That's not a regression -- it's what should have happened all along!
>
weird...it didn't happen with 2.6.14
> This says that the embedded hub in your stick needs 100 mA to run. You
> didn't say how much power is available from your host controller's port,
> but apparently it only provides 100 mA (otherwise the error message
> wouldn't have appeared).
nope, my hcd->power_budget is set to 500mA. This error is printed by
hub_port_connect_change in hub.c. The condition that refuses the new
device is not related to power budget, is it ?
Thanks
--
Franck
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