Hi Sergei, On 13 July 2015 18:10, Sergei wrote: > On 07/13/2015 07:55 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. <snip> Ok, so in summary, the max3355 device has two ways to communicate vbus back to a processor. You can either use the vbus signal or the status1/2 signals connected as gpios. The status1/2 signals give HNP information for OTG and are preferred, but depending on the board, they might not be available.
> >>> 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)? > > As I said, I planted the extcon hooks directly into USBHS (merged patch) > and USB HCD code (unmerged, low quality hack). Unless I am missing something, the problem I see with this is that it will not dynamically switch between Host and Gadget, hence my suggestion that the USB PHY driver be interested in the extcon events. > >>> 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? > > No, not working yet, I have other things on my plate still... Ok, thanks for your comments! Hopefully I'll find the time to have a stab at this. > >> 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 linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
