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To perform SuperSpeed compliance testing the port should first be placed into compliance mode. For xHCI 1.0 and prior this transition happens automatically when the port is in Training and encounters an LFPS timeout. Thus running compliance tests against a test appliance may simply just work by simply plugging in to the downstream port. However starting with xHCI 1.1 the transition from Polling.LFPS to compliance mode may be disabled by default and needs to be explicitly enabled by writing to the PLS field of the PORTSC register, which sets an internal 'CTE' (Compliance Transition Enabled) flag so that the port will perform the transition the next time it encounters LFPS timeout. Whether this is disabled or not is determined by the 'CTC' (Compliance Transition Capability) bit in the HCCPARAMS2 capability register. In order to allow a test operator to change this if needed, allow a test driver (such as drivers/usb/misc/lvstest.c) to send a SET_FEATURE(PORT_LINK_STATE) control message to the root hub to update the link state prior to connecting to the port. Subsequently, placing the port in warm reset would then disable the flag. Signed-off-by: Jack Pham <jackp@codeaurora.org> Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com> 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.