linux-kernel - [PATCH v1 7/7] iio: adc: ina2xx: Actually align the loop with the conversion ready flag

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Message-ID: <5b1a438b-4ea9-4905-b5af-abc383ebdf93@rwthex-w2-a.rwth-ad.de>
Date:   Fri, 8 Dec 2017 18:41:52 +0100
From:   Stefan Brüns <stefan.bruens@...h-aachen.de>
To:     <linux-iio@...r.kernel.org>
CC:     Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Stefan Brüns <stefan.bruens@...h-aachen.de>,
        Maciej Purski <m.purski@...sung.com>,
        <linux-kernel@...r.kernel.org>, "Andrew F . Davis" <afd@...com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        "Javier Martinez Canillas" <javier@....samsung.com>
Subject: [PATCH v1 7/7] iio: adc: ina2xx: Actually align the loop with the conversion ready flag

Currently, the logic just shifts the interval duration between the delay
and the polling, but never aligns to the conversion ready flag.

Whenever the conversion is already finished, schedule the next read on
the regular interval, otherwise schedule it one interval after the flag
bit has been set.

Split the work function in two functions, one for the status poll and one
for reading the values, to be able to note down the time when the flag
bit is raised.

Signed-off-by: Stefan Brüns <stefan.bruens@...h-aachen.de>

---

 drivers/iio/adc/ina2xx-adc.c | 57 +++++++++++++++++++++++++++++---------------
 1 file changed, 38 insertions(+), 19 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 0a6745e15a5d..728cc109a61c 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -697,13 +697,10 @@ static const struct iio_chan_spec ina219_channels[] = {
 	IIO_CHAN_SOFT_TIMESTAMP(4),
 };
 
-static int ina2xx_work_buffer(struct iio_dev *indio_dev)
+static int ina2xx_conversion_ready(struct iio_dev *indio_dev)
 {
 	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
-	/* data buffer needs space for channel data and timestap */
-	unsigned short data[4 + sizeof(s64)/sizeof(short)];
-	int bit, ret, i = 0;
-	s64 time;
+	int ret;
 	unsigned int alert;
 
 	/*
@@ -717,22 +714,29 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
 	 * For now, we do an extra read of the MASK_ENABLE register (INA226)
 	 * resp. the BUS_VOLTAGE register (INA219).
 	 */
-	if (!chip->allow_async_readout)
-		do {
-			if (chip->config->chip_id == ina226) {
-				ret = regmap_read(chip->regmap,
-						  INA226_MASK_ENABLE, &alert);
-				alert &= INA226_CVRF;
-			} else {
-				ret = regmap_read(chip->regmap,
-						  INA2XX_BUS_VOLTAGE, &alert);
-				alert &= INA219_CNVR;
-			}
+	if (chip->config->chip_id == ina226) {
+		ret = regmap_read(chip->regmap,
+				  INA226_MASK_ENABLE, &alert);
+		alert &= INA226_CVRF;
+	} else {
+		ret = regmap_read(chip->regmap,
+				  INA2XX_BUS_VOLTAGE, &alert);
+		alert &= INA219_CNVR;
+	}
 
-			if (ret < 0)
-				return ret;
+	if (ret < 0)
+		return ret;
 
-		} while (!alert);
+	return !!alert;
+}
+
+static int ina2xx_work_buffer(struct iio_dev *indio_dev)
+{
+	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
+	/* data buffer needs space for channel data and timestap */
+	unsigned short data[4 + sizeof(s64)/sizeof(short)];
+	int bit, ret, i = 0;
+	s64 time;
 
 	time = iio_get_time_ns(indio_dev);
 
@@ -776,6 +780,21 @@ static int ina2xx_capture_thread(void *data)
 	ktime_get_ts64(&next);
 
 	do {
+		while (!chip->allow_async_readout) {
+			ret = ina2xx_conversion_ready(indio_dev);
+			if (ret < 0)
+				return ret;
+
+			/*
+			 * If the conversion was not yet finished,
+			 * reset the reference timestamp.
+			 */
+			if (ret == 0)
+				ktime_get_ts64(&next);
+			else
+				break;
+		}
+
 		ret = ina2xx_work_buffer(indio_dev);
 		if (ret < 0)
 			return ret;
-- 
2.15.1