Hi Sergei, On 13 July 2015 17:37, Sergei wrote: > On 07/13/2015 06:02 PM, Phil Edworthy wrote: > > >>>>> Instead of statically selecting the PHY connection to either the > >>>>> USBHS (Function) or PCI0 (Host) IP blocks, this change allows the > >>>>> dts to specifiy gpio pins for the vbus and id signals. Additional > > >>>> These GPIOs don't have anything to do with the PHY, they're interfacing > > >> Perhaps that was too strong statement but nevertheless... > > > Looking at your MAX3355 extcon driver, I can't see how it would work on it's > > own. > > I've added the 'extcon' support into the Renesas USBHS driver, so that it > should be able to sense the ID pin status. > > > The system needs to sense vbus in order to determine that the board > > has been plugged into a USB Host. > > > Since the MAX3355 device doesn't > > directly provide any vbus signals, this shouldn't be part of the extcon driver, > > so where should it be? > > Sure, MAX3355 does provide voltage on Vbus, controlled by -OFFVBUS input. > It's just that the driver has only ID sensing support. > Do you have the MAX3355 datasheet at all? Sorry, I meant that the max3355 device does not directly provide vbus signals suitable for input as a gpio. Though as it provides the vbus signal to the usb connector, there is no reason this can't be used as a gpio input to rcar (just a level shifter needed ala the Koelsch board). > > On the other hand, the MAX3355 has a pair of status pins that can be used > > to get vbus instead. > > Sure, these bits reflect 4 OTG Vbus thresholds. > > > If these pins aren't used for other functions, maybe > > it's better to use these in the extcon driver. > > They are not. My comments were based on the view that vbus output from the max3355 device wasn't a signal that could be input to the rcar via gpio. Since it is, I agree that we should use that! > > My intention is to make the USB PHY driver listen for extcon events instead > > of directly accessing the ID and VBUS signals, but otherwise behave in the > > same way it currently does. > > I'm not sure the PHY driver should be interested in that... Then how is the PHY going to know when to switch between pci0 (host) and hsusb (function)? > > After reading some other threads, I also intend to set up a fixed regulator > > for the MAX3355 device to setup the shutdown and vbus enable pins. I know > > that the vbus enable should really be controlled some other way depending > > on the role, but for the moment I think it's ok just to enable it always. > > It's OK only in the host mode. > I don't think we need regulators. SHDN- is already supported by the driver > (though it only drives it high at start-up time), in fact it was the only reason > not to use gpio. > > > Do you think that is the correct way to progress this? > > I didn't have a clear picture how to implement the OTG support at the time > of writing the MAX3355 driver; actually, I was tasked to only support ID p[in > sensing. Right, so the max3355 driver needs some changes to include vbus handling. Are you working on this, or should I take it on? > Note that there's some ongoing effort now on linux-usb to support OTG > functionality. Yes, I need to spend some time reading that list! > > Thanks > > Phil > > WBR, Sergei Thanks Phil -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
