[PATCH] [TWL4030 MADC] Fix ADC[3:6] readings

[Peter Meerwald]

Hello,

adding linux-iio...

> To get a chance of this patch being considered for inclusion, you
> should send this to the maintainers of the phy and iio framework.
> There is a high chance, that none of them will see your mail.
> 
> On Thu, Jul 16, 2015 at 03:20:27PM -0700, Adam YH Lee wrote:
> > MADC[3:6] reads incorrect values without these two following changes:
> 
> uhm MADC[3:6] are externally available analog inputs. Your
> change will result in them being tied to the USB module.

change regarding TWL4030_USB_SEL_MADC_MCPC is necessary at 
least for some hardware revisions to get proper ADC values
 
> > - enable the 3v1 bias regulator for ADC[3:6]
> 
> The regulator is not required for correct MADC functionality, but
> for correct USB measureing. The regulator should not be requested
> by the madc module, but by the usb module, which is connected to
> the madc.

in my experience, the MADC exhibits several strange things, I wouldn't be 
surprised that this bias is somehow necessary for operation even if it is 
not what the spec says -- has this been tested?
 
> > - configure ADC[3:6] lines as input, not as USB
> 
> I don't think that should be done for all boards.
> 
> > [...]
> 
> -- Sebastian
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)