f624ec70b4
Add support for the SuperSpeed Link Layer test case TD.7.34
which requires the operator to place the port into compliance
mode, and to subsequently bring it out via reset. Historically
according to the (now deprecated) USB 3.0 specification a
SuperSpeed host downstream port would automatically transition
to Compliance mode from the Polling state if LFPS polling times
out. However the language in USB 3.1 as well as xHCI 1.1 states
it may be required to explicitly enable this transition. For
such hosts this is done by sending a SET_FEATURE(PORT_LINK_STATE)
with the state set to Compliance to the root hub port.
Similar to the other supported commands, to do this via sysfs:
echo > /sys/bus/usb/devices/2-0\:1.0/enable_compliance
According to xHCI 1.1 section 4.19.1.2.4.1, this enables the
transition to compliance mode upon LFPS timeout. Note that this
can only be issued when the port is in disconnected state. And
in order to disable this behavior on subsequent transitions, a
warm reset should be issued. So add another entry to do that:
echo > /sys/bus/usb/devices/2-0\:1.0/warm_reset
In general these attributes can also be useful for other USB
SuperSpeed compliance tests such as electrical and eye diagram
testing which require CPn patterns to be transmitted.
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.