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authorJack Pham <jackp@codeaurora.org>2021-07-20 11:09:07 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-07-21 11:06:47 +0300
commitbcacbf06c891374e7fdd7b72d11cda03b0269b43 (patch)
tree1d7ace15d4bc182a66801c95c7d4f6dd40840824 /drivers/usb/gadget/composite.c
parentfb4e52b609f0e29468b8f5b71117456410ff7d3b (diff)
downloadlinux-bcacbf06c891374e7fdd7b72d11cda03b0269b43.tar.xz
usb: gadget: composite: Allow bMaxPower=0 if self-powered
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>
Diffstat (limited to 'drivers/usb/gadget/composite.c')
-rw-r--r--drivers/usb/gadget/composite.c8
1 files 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