linux-kernel - Re: [PATCH 1/3] iio: Add Nuvoton NAU7802 ADC driver

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Date:	Mon, 22 Apr 2013 10:01:21 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC:	Shawn Guo <shawn.guo@...aro.org>,
	Grant Likely <grant.likely@...retlab.ca>, jimwall@...om,
	brian@...stalfontz.com, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	devicetree-discuss@...ts.ozlabs.org,
	Jonathan Cameron <jic23@....ac.uk>,
	Rob Landley <rob@...dley.net>,
	Rob Herring <rob.herring@...xeda.com>
Subject: Re: [PATCH 1/3] iio: Add Nuvoton NAU7802 ADC driver

Hi Alexandre,

Le 18/04/2013 17:38, Alexandre Belloni a écrit :
> +	nau7802_i2c_write(st, NAU7802_REG_PUCTRL, data);
> +	nau7802_i2c_write(st, NAU7802_REG_ADC_CTRL, 0x30);
> +
> +	if (tmp >= 2400) {
> +		data = NAU7802_CTRL1_VLDO((4500 - tmp) / 300);
> +		nau7802_i2c_write(st, NAU7802_REG_CTRL1, data);
> +	}

You should probably make a macro or inline function (with a comment) out
of that computation explaining why you are doing this.

> +
> +	st->min_conversions = 6;

I'd prefer to see this as a define.

> +
> +	/*
> +	 * The ADC fires continuously and we can't do anything about
> +	 * it. So we need to have the IRQ disabled by default, and we
> +	 * will enable them back when we will need them..
> +	 */
> +	if (client->irq) {
> +		irq_set_status_flags(client->irq, IRQ_NOAUTOEN);
> +		ret = request_threaded_irq(client->irq,
> +				NULL,
> +				nau7802_eoc_trigger,
> +				IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> +				client->dev.driver->name,
> +				idev);
> +		if (ret) {
> +			/*
> +			 * What may happen here is that our IRQ controller is
> +			 * not able to get level interrupt but this is required
> +			 * by this ADC as when going over 40 sample per second,
> +			 * the interrupt line may stay high between conversions.
> +			 * So, we continue no matter what but we switch to
> +			 * polling mode.
> +			 */
> +			dev_info(&client->dev,
> +				"Failed to allocate IRQ, using polling mode\n");
> +			client->irq = 0;
> +			/*
> +			 * We are polling, use the fastest sample rate by
> +			 * default
> +			 */
> +			st->sample_rate = 0x7;

Ditto.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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