On Wed, Oct 26, 2016 at 11:35:47AM +0300, Felipe Balbi wrote: > > Hi, > > Bin Liu <b-liu@xxxxxx> writes: > >> >> > There is no VBUS detection on this device and board. Is the VBUS > >> >> > detection needed for dwc3 to work in device mode? > >> >> > >> >> In the case of DRA7x, you don't *really* need detection. All you need to > >> >> do is correctly update UTMI mailbox. > >> > > >> > But the UTMI mailbox is driven by extcon events, right? The board > >> > doesn't have external circuit or gpio to detect VBUS. > >> > >> Then you should use ID event to *also* fiddle with VBUSVALID bit. That > >> used to work just fine, I guess commit below broke it: > > > > I don't understand how this dra7-evm worked before. dwc3 is in SS device > > mode, microB cable does not ground ID pin, so there is ID event when > > attach/detach dwc3 to the host. I am confused... > > Please read about the mailbox in your SoC. Try to figure out how it > works and what it does. What happens, internally, when you write > VBUS_VALID and/or IDGND bits. What does that mean to dwc3? When can dwc3 > connect its data pullups? What information does it need in order to do > that? Many of these questions will be answered ;-) Yes, got the issue figured out, it is missing hardware trigger to the mailbox. > > Hint: dwc3 doesn't know about any GPIOs or VBUS comparators or whatever > you may place in the PCB. DWC3 only understands PIPE3 and > ULPI/UTMI. So how does the mailbox come in the picture? Why do we need > it? Is it replacing any other component? Which component would that be? Thanks. -Bin. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
