On Fri, 2014-02-21 at 16:10 -0800, Dan Williams wrote: > From: Lan Tianyu <tianyu.lan@xxxxxxxxx> > > describe the mechanisms for controlling port power policy and > discovering the port power state. > > Cc: Oliver Neukum <oneukum@xxxxxxx> > Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx> > [sarah]: wordsmithing > [djbw]: updates for peer port changes > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > --- > Documentation/usb/power-management.txt | 237 ++++++++++++++++++++++++++++++++ > 1 files changed, 237 insertions(+), 0 deletions(-) > > diff --git a/Documentation/usb/power-management.txt b/Documentation/usb/power-management.txt > index 1392b61d6ebe..e67c1d4d1994 100644 > --- a/Documentation/usb/power-management.txt > +++ b/Documentation/usb/power-management.txt > @@ -5,6 +5,25 @@ > October 28, 2010 > > > + Contents: > + --------- > + * What is Power Management? > + * What is Remote Wakeup? > + * When is a USB device idle? > + * Forms of dynamic PM > + * The user interface for dynamic PM > + * Changing the default idle-delay time > + * Warnings > + * The driver interface for Power Management > + * The driver interface for autosuspend and autoresume > + * Other parts of the driver interface > + * Mutual exclusion > + * Interaction between dynamic PM and system PM > + * xHCI hardware link PM > + * USB Port Power Control > + * User Interface for Port Power Control > + * Suggested Userspace Port Power Policy > + > > What is Power Management? > ------------------------- > @@ -516,3 +535,221 @@ relevant attribute files is usb2_hardware_lpm. > driver will enable hardware LPM for the device. You > can write y/Y/1 or n/N/0 to the file to enable/disable > USB2 hardware LPM manually. This is for test purpose mainly. > + > + > + USB Port Power Control > + ---------------------- > + > +In addition to suspending endpoint devices and enabling hardware > +controlled link power management, the USB subsystem also has the > +capability to disable power to individual ports. Power is controlled Not necessary individual ports. You explain the limitations of ganged switching further below. I'd prefer "ports under some conditions" > +* wakeup note: the implementation does not allow a port connected to a > + device with wakeup capability to be powered off. The capability may be there. It just mustn't be enabled. Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
