On Thu, Sep 06, 2012 at 02:57:42PM -0400, Frank Agius wrote: > 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?
If MADC needs that regulator, it should request it as well so the regulator framework has correct usecounts. Also, IIRC there is a "suspend" mode for the regulator which won't power it down, but it will consume minimal power while mantaining MADC working. -- balbi
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