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
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