> -----Original Message----- > From: linux-omap-owner@xxxxxxxxxxxxxxx > [mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of Bill Gatliff > Sent: Thursday, March 18, 2010 3:05 AM > To: linux-omap@xxxxxxxxxxxxxxx > Subject: Question on OTG transceivers > > Guys: > > > I have a Beagleboard-like unit here that uses two SMSC USB3320C-EZK > PHYs: one for EHCI (usb1), the other for OTG (usb0). > > Two questions. First, the code in drivers/usb/otg/ulpi.c looks like it > might be what I need (my attempts so far with the "nop" transceiver have > ended in failure). Am I right? > Actually, the way the ehci-omap driver is currently written, it assumes the transceiver is present and available - you don't need a separate driver to access it. For that matter, the same probably holds for the OTG driver as well - you really don't need a driver for transparent transceivers like the SMSC332x. I'm not sure why the code was written this way to introduce NOP XCEIVs (need to go through the changelog to find out why, maybe). > Second, it looks like otg_set_transceiver() assumes there is only one > transceiver in the system. On a device like the OMAP3530 with multiple > ports, this seems like an odd assumption--- and one that clearly isn't > accurate for my platform. Or am I paying attention to the wrong stuff? > > Can anyone help navigate me through the trees in this forest? :) I think this assumption comes from some part of the OTG spec which says that OTG devices can have only one external USB port. But embedded devices can certainly have more than one transceiver (for example to connect an on-board USB device without exposing an external port) - so maybe there's no point keeping this restriction any more. - Anand-- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
