03f4492dbf
[ Upstream commit bcacbf06c891374e7fdd7b72d11cda03b0269b43 ] Currently the composite driver encodes the MaxPower field of the configuration descriptor by reading the c->MaxPower of the usb_configuration only if it is non-zero, otherwise it falls back to using the value hard-coded in CONFIG_USB_GADGET_VBUS_DRAW. However, there are cases when a configuration must explicitly set bMaxPower to 0, particularly if its bmAttributes also has the Self-Powered bit set, which is a valid combination. This is specifically called out in the USB PD specification section 9.1, in which a PDUSB device "shall report zero in the bMaxPower field after negotiating a mutually agreeable Contract", and also verified by the USB Type-C Functional Test TD.4.10.2 Sink Power Precedence Test. The fix allows the c->MaxPower to be used for encoding the bMaxPower even if it is 0, if the self-powered bit is also set. An example usage of this would be for a ConfigFS gadget to be dynamically updated by userspace when the Type-C connection is determined to be operating in Power Delivery mode. Co-developed-by: Ronak Vijay Raheja <rraheja@codeaurora.org> Acked-by: Felipe Balbi <balbi@kernel.org> Signed-off-by: Ronak Vijay Raheja <rraheja@codeaurora.org> Signed-off-by: Jack Pham <jackp@codeaurora.org> Link: https://lore.kernel.org/r/20210720080907.30292-1-jackp@codeaurora.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.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.