Re: BBB IIO ADC access not working

[Michael Welling <mwelling@ieee.org>]

On Tue, Aug 11, 2015 at 10:08:39AM -0700, Greg Wilson-Lindberg wrote:
> Hi Michael, 
> 
> > -----Original Message-----
> > From: Michael Welling [mailto:mwelling79@gmail.com] On Behalf 
> > Of Michael Welling
> > Sent: Tuesday, August 11, 2015 10:03 AM
> > To: Greg Wilson-Lindberg
> > Cc: Michael Welling; Daniel Baluta; linux-iio@vger.kernel.org
> > Subject: Re: BBB IIO ADC access not working
> > 
> > On Tue, Aug 11, 2015 at 09:00:21AM -0700, Greg Wilson-Lindberg wrote:
> > > Hello Michael,
> > > 
> > > .....
> > > > Try increasing the charge-delay and see if you can find a value 
> > > > where it stops happening.
> > > > 
> > > > Something tells me that it won't fix the issue.
> > > > 
> > > > Where is the source tree for this kernel?
> > > > Which dtb are you using?
> > > >  
> > > 
> > > I increased the charge-delay to 0x10000 and left the system 
> > over night 
> > > with no user interaction and it was locked up this morning, I think 
> > > I'm going to have to agree that changing that to a larger 
> > number will not fix the problem.
> > > 
> > > Here is a link to the dts that we use:
> > > http://pastebin.com/5nU27sML
> > > I did not include the standard dtsi files that we include from the 
> > > linux source tree, just the files that we built ourselves 
> > or that we modified.
> > 
> > I do not see the modification that you made to the 
> > touchscreen registration.
> 
> We haven't modified the touch screen registration, we use xinput_calibrator for the calibration.
> > 
> > Guessing you modified this file for the charge-delay:
> > https://github.com/beagleboard/linux/blob/3.14.40-ti-r62/arch/
> > arm/boot/dts/am335x-bone-ti-tscadc-4-wire.dtsi
> 
> And you are correct, I forgot that I had added the charge-delay parameter to the 
> am335x-bone-ti-tscadc-4-wire.dtsi file, sorry.
> 
> > 
> > > 
> > > RCN replied thusly to my request for the source tree:
> > >    Here's the kernel source, the config we use is "bb.org_defconfig"
> > >    https://github.com/beagleboard/linux/tree/3.14.40-ti-r62
> > > 
> > > Thanks for your help in tracking down this problem.
> > 
> > I will compare the drivers in this kernel to the latest work 
> > in the mainline.

Looking at the commit logs, I see no mention of this type of behavior in either
kernel.


Here is something that never landed in the mainline kernel:
https://github.com/beagleboard/linux/commit/e655e2f723a4e78a47868f766e4c141deca5e234

Have you tried a more recent kernel release to see if this behavior is still
occurring?

> > 
> > > 
> > > Regards,
> > > Greg
> >