iio: adc: ad7793: claim direct mode when writing frequency

PATCH Applied Alison Schofield 3 participants 3 messages Jun 2, 2016 – Jun 3, 2016

Subsystems (2)

IIO Analog Devices IIO drivers

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Alison Schofield

author

2016-06-02 04:28 UTC #0 lore raw

PATCH v2 3/7 iio: adc: ad7793: claim direct mode when writing frequency

Driver was checking for direct mode and trying to lock it, but left a gap where mode could change before the desired operation. Use iio_device_claim_direct_mode() to guarantee device stays in direct mode.

Refactor function to clarify look-up followed by lock sequence.

Signed-off-by Alison Schofield <[email protected]>

Cc Daniel Baluta <[email protected]>

---
Changes in v2
Refactored function per reviewers comments
Updated changelog

 drivers/iio/adc/ad7793.c | 32 +++++++++++++-------------------
 1 file changed, 13 insertions(+), 19 deletions(-)

drivers/iio/adc/ad7793.c +13 ~~-19~~

index 7b07bb6..a43722f 100644
@@ -369,13 +369,6 @@ static ssize_t ad7793_write_frequency(struct device *dev,
 	long lval;
 	int i, ret;
 
-	mutex_lock(&indio_dev->mlock);
-	if (iio_buffer_enabled(indio_dev)) {
-		mutex_unlock(&indio_dev->mlock);
-		return -EBUSY;
-	}
-	mutex_unlock(&indio_dev->mlock);
-
 	ret = kstrtol(buf, 10, &lval);
 	if (ret)
 		return ret;

@@ -383,20 +376,21 @@ static ssize_t ad7793_write_frequency(struct device *dev,
 	if (lval == 0)
 		return -EINVAL;
 
-	ret = -EINVAL;
-
 	for (i = 0; i < 16; i++)
-		if (lval == st->chip_info->sample_freq_avail[i]) {
-			mutex_lock(&indio_dev->mlock);
-			st->mode &= ~AD7793_MODE_RATE(-1);
-			st->mode |= AD7793_MODE_RATE(i);
-			ad_sd_write_reg(&st->sd, AD7793_REG_MODE,
-					 sizeof(st->mode), st->mode);
-			mutex_unlock(&indio_dev->mlock);
-			ret = 0;
-		}
+		if (lval == st->chip_info->sample_freq_avail[i])
+			break;
+	if (i == 16)
+		return -EINVAL;
 
-	return ret ? ret : len;
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+	st->mode &= ~AD7793_MODE_RATE(-1);
+	st->mode |= AD7793_MODE_RATE(i);
+	ad_sd_write_reg(&st->sd, AD7793_REG_MODE, sizeof(st->mode), st->mode);
+	iio_device_release_direct_mode(indio_dev);
+
+	return len;
 }
 
 static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,

Signature · 1 line

2.1.4

Lars-Peter Clausen

Acked-by on v2 3/7

2016-06-02 08:37 UTC #1 lore raw

Quoted 9 lines · Alison Schofield

Driver was checking for direct mode and trying to lock it, but left a gap where mode could change before the desired operation. Use iio_device_claim_direct_mode() to guarantee device stays in direct mode.
Refactor function to clarify look-up followed by lock sequence.
Signed-off-by Alison Schofield <[email protected]>
Cc Daniel Baluta <[email protected]>

Looks good, thanks.

Acked-by Lars-Peter Clausen <[email protected]>

Jonathan Cameron

maintainer Applied

2016-06-03 12:02 UTC #2 lore raw

Quoted 6 lines · Lars-Peter Clausen

Quoted 5 lines · Alison Schofield
Driver was checking for direct mode and trying to lock it, but left a gap where mode could change before the desired operation. Use iio_device_claim_direct_mode() to guarantee device stays in direct mode.

Quoted 8 lines

Quoted 4 lines
Refactor function to clarify look-up followed by lock sequence.
Signed-off-by Alison Schofield <[email protected]>
Cc Daniel Baluta <[email protected]>
Looks good, thanks.
Acked-by Lars-Peter Clausen <[email protected]>

Applied to the togreg branch of iio.git - initially pushed out as testing for the autobuilders to play with it.

Thanks,

Jonathan

Quoted 5 lines

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