linux-kernel - [PATCH 3/5 v3] iio: exynos_adc: reduce timeout and use wait_for_completion

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Date:	Wed, 30 Apr 2014 14:56:53 +0530
From:	Naveen Krishna Chatradhi <ch.naveen@...sung.com>
To:	linux-iio@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	dianders@...omium.org, gregkh@...uxfoundation.org,
	naveenkrishna.ch@...il.com, lars@...afoo.de, cpgs@...sung.com,
	grundler@...omium.org, t.figa@...sung.com
Subject: [PATCH 3/5 v3] iio: exynos_adc: reduce timeout and use
 wait_for_completion_timeout

ADC module on Exynos5 SoCs runs at 600KSPS. At this conversion rate,
waiting for 1000 msecs is wasteful (incase of h/w failure).

Hence, reduce the time out to 100msecs and use
wait_for_completion_timeout() instead of
wait_for_completion_interruptible_timeout()

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@...sung.com>
Reviewed-by: Doug Anderson <dianders@...omium.org>
---
Changes since v2:
None
Changes since v1:
None
v0:
This change is a part of the patch reviewd at https://lkml.org/lkml/2013/11/5/92

 drivers/iio/adc/exynos_adc.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
index ff98c5d..939aaf7 100644
--- a/drivers/iio/adc/exynos_adc.c
+++ b/drivers/iio/adc/exynos_adc.c
@@ -82,7 +82,7 @@ enum adc_version {
 #define ADC_CON_EN_START	(1u << 0)
 #define ADC_DATX_MASK		0xFFF
 
-#define EXYNOS_ADC_TIMEOUT	(msecs_to_jiffies(1000))
+#define EXYNOS_ADC_TIMEOUT	(msecs_to_jiffies(100))
 
 struct exynos_adc {
 	void __iomem		*regs;
@@ -121,6 +121,7 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
 	struct exynos_adc *info = iio_priv(indio_dev);
 	unsigned long timeout;
 	u32 con1, con2;
+	int ret;
 
 	if (mask != IIO_CHAN_INFO_RAW)
 		return -EINVAL;
@@ -145,16 +146,19 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
 				ADC_V1_CON(info->regs));
 	}
 
-	timeout = wait_for_completion_interruptible_timeout
+	timeout = wait_for_completion_timeout
 			(&info->completion, EXYNOS_ADC_TIMEOUT);
-	*val = info->value;
+	if (timeout == 0) {
+		ret = -ETIMEDOUT;
+	} else {
+		*val = info->value;
+		*val2 = 0;
+		ret = IIO_VAL_INT;
+	}
 
 	mutex_unlock(&indio_dev->mlock);
 
-	if (timeout == 0)
-		return -ETIMEDOUT;
-
-	return IIO_VAL_INT;
+	return ret;
 }
 
 static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
-- 
1.7.9.5

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