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Commit 5748150e authored by José Miguel Gonçalves's avatar José Miguel Gonçalves Committed by Linus Torvalds
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drivers/hwmon/adcxx.c: fix for single-channel ADCs 



While testing an ADC121S021 in an embedded board with a S3C2142 SoC (ARM
core), I have found that the 'adcxx' driver does not handle correctly
single channel ADCs from this chip family.  For single channel chips you
must only issue one read transfer for correct measurement.

Signed-off-by: default avatarJose Miguel Goncalves <jose.goncalves@inov.pt>
Cc: Marc Pignat <marc.pignat@hevs.ch>
Cc: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4cae7878

drivers/hwmon/adcxx.c

+10 −5
Original line number Original line Diff line number Diff line
@@ -62,18 +62,23 @@ static ssize_t adcxx_read(struct device *dev, 
	struct spi_device *spi = to_spi_device(dev);

	struct spi_device *spi = to_spi_device(dev);

	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);

	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);

	struct adcxx *adc = dev_get_drvdata(&spi->dev);

	struct adcxx *adc = dev_get_drvdata(&spi->dev);

	u8 tx_buf[2] = { attr->index << 3 }; /* other bits are don't care */

	u8 tx_buf[2];

	u8 rx_buf[2];

	u8 rx_buf[2];

	int status;

	int status;

	int value;

	u32 value;





	if (mutex_lock_interruptible(&adc->lock))

	if (mutex_lock_interruptible(&adc->lock))

		return -ERESTARTSYS;

		return -ERESTARTSYS;





	if (adc->channels == 1) {

		status = spi_read(spi, rx_buf, sizeof(rx_buf));

	} else {

		tx_buf[0] = attr->index << 3; /* other bits are don't care */

		status = spi_write_then_read(spi, tx_buf, sizeof(tx_buf),

		status = spi_write_then_read(spi, tx_buf, sizeof(tx_buf),

						rx_buf, sizeof(rx_buf));

						rx_buf, sizeof(rx_buf));

	}

	if (status < 0) {

	if (status < 0) {

		dev_warn(dev, "spi_write_then_read failed with status %d\n",

		dev_warn(dev, "SPI synch. transfer failed with status %d\n",

				status);

				status);

		goto out;

		goto out;

	}

	}