Hi Balbi,

Glad to see the OTG mode is prepare to support in your dwc3-role-switch
branch. But it is not fit for intel Merrfield/Moorfield platforms. :(

The reason is we implemented DRD mode instead of OTG mode. So the
GCTL.PortCapDir will be set as 01 for host mode, and 10 for device mode.

And the most important thing is we implemented two low power states for
dwc3 controller. D0i3hot and D0i3cold.

If no cable connected, we will trigger D0i3cold which will power gate
every clock/power used by dwc3 controller.

And entering D0i3hot with hibernation mode when acting as host mode
(micro A cable connected), also during device mode(micro B cable connected
to PC host).

For ID/VBus detection, we are using PMIC to do detect. So we will also
power gate the USB PHY for D0i3cold.

When we plug in micro A/B cable, the PMIC will report the ID/VBus change
event, then driver will force controller resume to D0 from D0i3cold. Due
to we haven't do any backup before entering D0i3cold, so we have to
re-initialize all host/device portion registers with setting
GCTL.PortCapDir to 01 or 10.

So with this PM design and DRD mode, we can't use your OTG mode. :(
I want to get your suggestions for DRD mode of dwc3 driver.

We add DRD support based on your otg.c or create new file drd.c?

Thanks
Yu
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to