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| author | Jack Pham <jackp@codeaurora.org> | 2021-07-20 11:09:07 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-21 11:06:47 +0300 |
| commit | bcacbf06c891374e7fdd7b72d11cda03b0269b43 (patch) | |
| tree | 1d7ace15d4bc182a66801c95c7d4f6dd40840824 | |
| parent | fb4e52b609f0e29468b8f5b71117456410ff7d3b (diff) | |
| download | linux-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>
| -rw-r--r-- | drivers/usb/gadget/composite.c | 8 |
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 |