On Tue, Oct 22, 2019 at 11:57:53PM -0700, Jack Pham wrote:
> USB 3.x SuperSpeed peripherals can draw up to 900mA of VBUS power
> when in configured state. However, if a configuration wanting to
> take advantage of this is added with MaxPower greater than 500
> (currently possible if using a ConfigFS gadget) the composite
> driver fails to accommodate this for a couple reasons:
>
> - usb_gadget_vbus_draw() when called from set_config() and
> composite_resume() will be passed the MaxPower value without
> regard for the current connection speed, resulting in a
> violation for USB 2.0 since the max is 500mA.
>
> - the bMaxPower of the configuration descriptor would be
> incorrectly encoded, again if the connection speed is only
> at USB 2.0 or below, likely wrapping around UINT8_MAX since
> the 2mA multiplier corresponds to a maximum of 610mA.
^^^^^
Argh, my bad math/typo. Should be 510mA (UINT8_MAX = 255 * 2mA).
Jack
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