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

[jbe@pengutronix.de (Jürgen Beisert)]

On Monday 23 September 2013 15:24:37 J?rgen Beisert wrote:
> Hi Lothar,
>
> On Monday 23 September 2013 14:12:02 Lothar Wa?mann 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.

Hmmm: 24 MHz / 750  = CLK_32K / 16 = CLK_LRADC2K

Regards,
Juergen

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