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When a USB device attached to a root-hub port sends a wakeup request to a sleeping system, we do not report the wakeup event to the PM core. This is because a system resume involves waking up all suspended USB ports as quickly as possible; without the normal USB_RESUME_TIMEOUT delay, the host controller driver doesn't set the USB_PORT_STAT_C_SUSPEND flag and so usb_port_resume() doesn't realize that a wakeup request was received. However, some environments (such as Chrome OS) want to have all wakeup events reported so they can be ascribed to the appropriate device. To accommodate these environments, this patch adds a new routine to the hub driver and a corresponding new HCD method to be used when a root hub resumes. The HCD method returns a bitmap of ports that have initiated a wakeup signal but not yet completed resuming. The hub driver can then report to the PM core that the child devices attached to these ports initiated a wakeup event. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Suggested-by: Anshuman Gupta <anshuman.gupta@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.