[U-Boot] [PATCH 17/17] sunxi: Hookup OTG USB controller support

Siarhei Siamashka
2015-02-09T03:54:04Z

On Sat, 31 Jan 2015 04:54:47 +0200
Siarhei Siamashka <siarhei.siamashka@gmail.com> wrote:

> On Sun, 11 Jan 2015 20:34:55 +0100
> Hans de Goede <hdegoede@redhat.com> wrote:
>
> > Hookup OTG USB controller support and enable the otg controller + USB-keyb
> > on various tablets.
> >
> > This allows tablet owners to interact with u-boot without needing to solder
> > a serial console onto their tablet PCB.
>
> Thanks. Works great on my Primo73 and Primo81 tablets. However I have
> just one naive question before happily taking it into use by default.
>
> Is the hardcoded otg host mode (without checking the id pin) always
> safe? For example, what happens if somebody connects a charger instead
> of a usb keyboard to the tablet?

So, does anyone have any idea if it is theoretically safe to have two
USB hosts connected to each other and both driving VBUS at +5V?

A somewhat realistic scenario is booting an Allwinner tablet over
USB using the FEL mode. Is it a good idea for such tablet to have
CONFIG_USB_MUSB_SUNXI=y and CONFIG_USB0_VBUS_PIN="axp_drivebus"
in defconfig?

--
Best regards,
Siarhei Siamashka