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iio: dht11: Improve detection of sensor type 

The old code was based on a DHT11 datasheet which specifies a measurement
range of 20%-90% RH. Turns out the sensor actually reports values outside
this range, so we should support it as far as possible.

Reported-by: Edward Attfield <edward@attfield.ca>
Signed-off-by: Harald Geyer <harald@ccbib.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Harald Geyer 2018-02-11 11:09:40 +00:00 committed by Jonathan Cameron
parent 7fe2241c0e
commit a6bffb6920
1 changed files with 1 additions and 1 deletions
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2
drivers/iio/humidity/dht11.c
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@ -159,7 +159,7 @@ static int dht11_decode(struct dht11 *dht11, int offset)
}
dht11->timestamp = ktime_get_boot_ns();
if (hum_int < 20) { /* DHT22 */
if (hum_int < 4) { /* DHT22: 100000 = (3*256+232)*100 */
dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
((temp_int & 0x80) ? -100 : 100);
dht11->humidity = ((hum_int << 8) + hum_dec) * 100;