Re: [PATCH] iio: dht11: Improve detection of sensor type

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 11 Feb 2018 11:09:40 +0000
Harald Geyer <harald@ccbib.org> wrote:

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

Thanks,

Jonathan

> ---
>  drivers/iio/humidity/dht11.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
> index df6bab4..1a9f8f4 100644
> --- a/drivers/iio/humidity/dht11.c
> +++ b/drivers/iio/humidity/dht11.c
> @@ -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;