linux-kernel - Re: [PATCH 4/4] iio: ti_am335x_adc: Add continuous sampling and trigger support

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Message-ID: <20130816132549.GD1263@linutronix.de>
Date:	Fri, 16 Aug 2013 15:25:49 +0200
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	Zubair Lutfullah <zubair.lutfullah@...il.com>
Cc:	jic23@....ac.uk, dmitry.torokhov@...il.com,
	linux-iio@...r.kernel.org, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
	Russ.Dill@...com
Subject: Re: [PATCH 4/4] iio: ti_am335x_adc: Add continuous sampling and
 trigger support

* Zubair Lutfullah | 2013-08-13 21:05:03 [+0100]:

>diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
>index 3ceac3e..0d7e313 100644
>--- a/drivers/iio/adc/ti_am335x_adc.c
>+++ b/drivers/iio/adc/ti_am335x_adc.c
>@@ -141,58 +350,51 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
> {
…
>+	if (iio_buffer_enabled(indio_dev))
>+		return -EBUSY;
>+	else {

You can drop else so you lose one ident level.

>+		unsigned long timeout = jiffies + usecs_to_jiffies
>+					(IDLE_TIMEOUT * adc_dev->channels);

What computing this once? ->channels is assigned at probe time.

>+		step_en = get_adc_step_mask(adc_dev);
>+		am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
>+
>+		/* Wait for ADC sequencer to complete sampling */
>+		while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) {
>+			if (time_after(jiffies, timeout))
>+				return -EAGAIN;

You should check the condition after the timeout occured once again. It
is possible that the task performing the read has been pushed away by a
higher prio task (or preempted incase this sounds like a bully) and
after it got back on the cpu the timeout occured but the condition is
valid and no reason for -EAGAIN.

>+			}
and the bracket needs to left by one tab.

Sebastian
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