Jack Pham <jackp@xxxxxxxxxxxxxx> writes: > 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@xxxxxxxxxxxxxx> > Signed-off-by: Ronak Vijay Raheja <rraheja@xxxxxxxxxxxxxx> > Signed-off-by: Jack Pham <jackp@xxxxxxxxxxxxxx> Nice catch! Acked-by: Felipe Balbi <balbi@xxxxxxxxxx> -- balbi
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