Re: [PATCH 1/9] Staging/iio/adc/touchscreen/MXS: add proper clock handling

["Jürgen Beisert" <jbe-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

Hi Lothar,

On Monday 23 September 2013 17:30:18 Lothar Waßmann wrote:
> > [...]
> > @@ -928,6 +931,9 @@ static int mxs_lradc_probe(struct platform_device
> > *pdev) if (IS_ERR(lradc->base))
> >  		return PTR_ERR(lradc->base);
> >
> > +	lradc->clk = devm_clk_get(&pdev->dev, NULL);
> > +	clk_prepare_enable(lradc->clk);
> > +
>
> Wouldn't it make sense to enable the clock only when the device is
> opened to save power while not actually in use?

Sure. But I haven't analyzed yet if the IIO part of the driver also uses the 
delay units and - more important - when it use them.

@Marek: can you tell us, where the clock should be enabled in your part of the 
driver (if required)?

BTW: do we also need to get and enable the 24 MHz clock (used by the ADC 
itself)? I'm not sure if this clock is the "CLK_ANA24M" shown in 
their "Logical Diagram of Clock Domains". The datasheets also mention 
the "clk_xtal24m" clock for "analog 24 MHz clock domains". But does "Fixed 
clock domains" mean they are not switchable and thus always enabled?

Regards,
Juergen

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