From: Jack Pham <jackp@xxxxxxxxxxxxxx> [ 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@xxxxxxxxxxxxxx> Acked-by: Felipe Balbi <balbi@xxxxxxxxxx> Signed-off-by: Ronak Vijay Raheja <rraheja@xxxxxxxxxxxxxx> Signed-off-by: Jack Pham <jackp@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210720080907.30292-1-jackp@xxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/usb/gadget/composite.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c index d85bb3ba8263..a76ed4acb570 100644 --- a/drivers/usb/gadget/composite.c +++ b/drivers/usb/gadget/composite.c @@ -481,7 +481,7 @@ static u8 encode_bMaxPower(enum usb_device_speed speed, { unsigned val; - if (c->MaxPower) + if (c->MaxPower || (c->bmAttributes & USB_CONFIG_ATT_SELFPOWER)) val = c->MaxPower; else val = CONFIG_USB_GADGET_VBUS_DRAW; @@ -891,7 +891,11 @@ static int set_config(struct usb_composite_dev *cdev, } /* when we return, be sure our power usage is valid */ - power = c->MaxPower ? c->MaxPower : CONFIG_USB_GADGET_VBUS_DRAW; + if (c->MaxPower || (c->bmAttributes & USB_CONFIG_ATT_SELFPOWER)) + power = c->MaxPower; + else + power = CONFIG_USB_GADGET_VBUS_DRAW; + if (gadget->speed < USB_SPEED_SUPER) power = min(power, 500U); else -- 2.30.2
