33e321586e
After xHC controller is started, either in probe or resume, it can take a while before any of the connected usb devices are visible to the roothub due to link training. It's possible xhci driver loads, sees no acivity and suspends the host before the USB device is visible. In one testcase with a hotplugged xHC controller the host finally detected the connected USB device and generated a wake 500ms after host initial start. If hosts didn't suspend the device duringe training it probablty wouldn't take up to 500ms to detect it, but looking at specs reveal USB3 link training has a couple long timeout values, such as 120ms RxDetectQuietTimeout, and 360ms PollingLFPSTimeout. So Add a 500ms grace period that keeps polling the roothub for 500ms after start, preventing runtime suspend until USB devices are detected. Cc: stable@vger.kernel.org Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Link: https://lore.kernel.org/r/20220825150840.132216-3-mathias.nyman@linux.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.
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.