Messages in this thread | | | Date | Mon, 13 Jul 2015 19:37:11 +0300 | From | Sergei Shtylyov <> | Subject | Re: [PATCH v3] phy: rcar-gen2 usb: Add Host/Function switching for USB0 |
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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?
> 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 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...
> 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. Note that there's some ongoing effort now on linux-usb to support OTG functionality.
> Thanks > Phil
WBR, Sergei
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