This is a note to let you know that I've just added the patch titled
usb: gadget: composite: Allow bMaxPower=0 if self-powered
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadget-composite-allow-bmaxpower-0-if-self-power.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ed98e460ae007125e6c1b320339172b91e1327a2
Author: Jack Pham <jackp@xxxxxxxxxxxxxx>
Date: Tue Jul 20 01:09:07 2021 -0700
usb: gadget: composite: Allow bMaxPower=0 if self-powered
[ 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>
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
