On Wed, Dec 23, 2015 at 05:21:25PM +0000, Jonathan Cameron wrote:

On 23 December 2015 10:48:33 GMT+00:00, Ludovic Desroches [off-list ref] wrote:

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On Wed, Dec 23, 2015 at 11:27:00AM +0100, Ludovic Desroches wrote:

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On Tue, Dec 22, 2015 at 06:34:00PM +0000, Jonathan Cameron wrote:

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On 21/12/15 09:24, Ludovic Desroches wrote:

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This driver supports the new version of the Atmel ADC device

introduced

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with the SAMA5D2 SoC family.

[...]

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+static irqreturn_t at91_adc_interrupt(int irq, void *private)
+{
+	struct iio_dev *indio = private;
+	struct at91_adc_state *st = iio_priv(indio);
+	u32 status = at91_adc_readl(st, ADC_ISR);
+
+	status &= at91_adc_readl(st, ADC_IMR);
+	if (status & 0xFFF) {
+		st->last_value = at91_adc_readl(st, st->chan->address);

If this is a polled read - is there any reason to read this value

here

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rather than outside the interrupt?

No it can be done outside the interrupt. I have taken some parts from

the

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previous driver but it was reading a register used by all the

channels

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when it has been designed. So yes there is probably no more reason to
read it into the interrupt.

Thinking about it. Is it really useful to move reading outside the
interrupt?

It avoids needing to know the channel in here, hence simplifying the code a bit.

I am not sure it will simplify the code since the interrupt is cleared
when reading the conversion not the interrupt status register.

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By the way this is not a polled read.

I meant that it is an individually requested conversion rather than a free running
 sampling system where the value read might change before it is read out.

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+		st->done = true;
+		wake_up_interruptible(&st->wq_data_available);
+	}
+
+	return IRQ_HANDLED;
+}

Ludovic
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