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staging:iio:hmc5843: Implement timeout in read function 

avoid polling data ready bit forever; msleep() may be too long
for high sampling frequencies but the driver interface does not
support buffering

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Cc: Shubhrajyoti Datta <shubhrajyoti@ti.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Peter Meerwald 2013-07-27 16:31:00 +01:00 committed by Jonathan Cameron
parent a34778f3a7
commit 4dedf31cd1
1 changed files with 15 additions and 3 deletions
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18
drivers/staging/iio/magnetometer/hmc5843.c
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@ -26,6 +26,7 @@
#include <linux/types.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/delay.h>
#define HMC5843_CONFIG_REG_A 0x00
#define HMC5843_CONFIG_REG_B 0x01
@ -210,11 +211,22 @@ static int hmc5843_read_measurement(struct iio_dev *indio_dev,
struct i2c_client *client = to_i2c_client(indio_dev->dev.parent);
struct hmc5843_data *data = iio_priv(indio_dev);
s32 result;
int tries = 150;
mutex_lock(&data->lock);
result = i2c_smbus_read_byte_data(client, HMC5843_STATUS_REG);
while (!(result & HMC5843_DATA_READY))
result = i2c_smbus_read_byte_data(client, HMC5843_STATUS_REG);
while (tries-- > 0) {
result = i2c_smbus_read_byte_data(client,
HMC5843_STATUS_REG);
if (result & HMC5843_DATA_READY)
break;
msleep(20);
}
if (tries < 0) {
dev_err(&client->dev, "data not ready\n");
mutex_unlock(&data->lock);
return -EIO;
}
result = i2c_smbus_read_word_data(client, address);
mutex_unlock(&data->lock);