From: Jack Pham jackp@codeaurora.org
[ 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 --- 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 72a9797dbbae..504c1cbc255d 100644 --- a/drivers/usb/gadget/composite.c +++ b/drivers/usb/gadget/composite.c @@ -482,7 +482,7 @@ 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; @@ -936,7 +936,11 @@ 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