[PATCHv5] staging/iio/adc: change the MXS touchscreen driver implementation

[Jürgen Beisert]

Hi Lothar,

On Monday 23 September 2013 14:12:02 Lothar Waßmann wrote:
> [...]
> > @Lothar: What kernel revision did you use? I had to go back to 3.9 to get
> > a
>
> Current linux-next (3.12-rc1).

Okay.

> > working kernel on the MX28EVK. More recent vanilla kernels stop working
> > (MMC and network fail here).
>
> I'm seeing some messages:
> |mxs-mmc 80010000.ssp: dummy supplies not allowed
> |fec 800f0000.ethernet: dummy supplies not allowed

It was my fault. I'm also working with 3.12-rc1 now.

> But without any apparent consequences. Maybe that's a problem with the
> MX28EVK?

It seems the LRADC delay feature does not work. The touch detection interrupt 
happens and the driver switches to the Y plate measurement, arms the LRADC 
delay unit ... and nothing more happens. The LRADC delay unit should start a 
conversion on ADC channel 4. But it does not. Never.

The i.MX28 manual says the LRADC delay unit is driven by a 2 kHz clock, but 
does not say what kind of clock it is (or is derived from). I guess now, this 
clock isn't enabled and thus the delay unit can't work. At least on the 
MX28EVK. On your TX28 platform the clock seems enabled and the delay unit can 
do its job and drive the state machine.

Regards,
Juergen

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