linux-kernel - [PATCH] iio: chemical: bme680: Fix pressure and humidity ABI mismatch

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Date:   Thu,  8 Aug 2019 21:13:50 +0530
From:   Himanshu Jha <himanshujha199640@...il.com>
To:     jic23@...nel.org
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        dpfrey@...il.com, mike.looijmans@...ic.nl,
        Himanshu Jha <himanshujha199640@...il.com>
Subject: [PATCH] iio: chemical: bme680: Fix pressure and humidity ABI mismatch

Standard ABI for reporting pressure is kilopascal and for
relative humidity it is millipercent.

What:           /sys/bus/iio/devices/iio:deviceX/in_pressureY_input
What:           /sys/bus/iio/devices/iio:deviceX/in_pressure_input
KernelVersion:  3.8
Contact:        linux-iio@...r.kernel.org
Description:
                Scaled pressure measurement from channel Y, in kilopascal.

What:           /sys/bus/iio/devices/iio:deviceX/in_humidityrelative_input
KernelVersion:  3.14
Contact:        linux-iio@...r.kernel.org
Description:
                Scaled humidity measurement in milli percent.

Currently pressure is reported in hectopascal(hPa) and relative humidity
in percent. Hence fix this ABI mismatch conforming to the standard ABI.

Fixes: 1b3bd8592780 ("iio: chemical: Add support for Bosch BME680 sensor")
Signed-off-by: Himanshu Jha <himanshujha199640@...il.com>
---

While cleaning this mess I wonder about the gas channel and there
exists no `in_resistance_input` in standard ABI :-(

We only have:

What:           /sys/bus/iio/devices/iio:deviceX/in_resistance_raw
What:           /sys/bus/iio/devices/iio:deviceX/in_resistanceX_raw
What:           /sys/bus/iio/devices/iio:deviceX/out_resistance_raw
What:           /sys/bus/iio/devices/iio:deviceX/out_resistanceX_raw
KernelVersion:  4.3
Contact:        linux-iio@...r.kernel.org
Description:
                Raw (unscaled no offset etc.) resistance reading that can be processed
                into an ohm value.

The sensor outputs processed value which is reported as is.

So, does it need a new ABI ?

 drivers/iio/chemical/bme680_core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/chemical/bme680_core.c b/drivers/iio/chemical/bme680_core.c
index ccde4c65ff93..28cc96d1e3c8 100644
--- a/drivers/iio/chemical/bme680_core.c
+++ b/drivers/iio/chemical/bme680_core.c
@@ -670,7 +670,7 @@ static int bme680_read_press(struct bme680_data *data,
 	}
 
 	*val = bme680_compensate_press(data, adc_press);
-	*val2 = 100;
+	*val2 = 1000;
 	return IIO_VAL_FRACTIONAL;
 }
 
@@ -704,7 +704,7 @@ static int bme680_read_humid(struct bme680_data *data,
 	comp_humidity = bme680_compensate_humid(data, adc_humidity);
 
 	*val = comp_humidity;
-	*val2 = 1000;
+	*val2 = 1000000;
 	return IIO_VAL_FRACTIONAL;
 }
 
-- 
2.17.1