I'm seeing what I think is an unintended consequence of powering down
the USB phy. All the relavent code is in file twl4030_usb.c. My system
is setup to use the USB in otg mode. If nothing is connected to the USB
OTG port, the phy suspension code is called. In the chain of calls that
follows, the vusb3v1 regulator is disabled. However, according to the
OMAP power management manual, vusb3v1 is used "to bias the analog
multiplexers on the four MCPC pins between the carkit and the MADC".
I've seen if there is no bias on this mux, the MADC driver returns
incorrect counts on these 4 pins that should be in A/D mode. If I plug
something into the USB OTG port, the MADC driver returns the expected
counts. I also created a debug version of the twl4030-usb driver, with
the disabling of the vusb3v1 commented out and the MADC returns the
correct counts regardless of the state of the USB OTG port.
Since the vusb3v1 regulator is required for the proper operation of the
mux and by extension the MADC and carkit mode, shouldn't it always be
enabled?
frank
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
