iio: inkern: apply consumer scale when no channel scale is available

BugLink: https://bugs.launchpad.net/bugs/1971497
commit 14b457fdde38de594a4bc4bd9075019319d978da upstream.

When a consumer calls iio_read_channel_processed() and no channel scale
is available, it's assumed that the scale is one and the raw value is
returned as expected.

On the other hand, if the consumer calls iio_convert_raw_to_processed()
the scaling factor requested by the consumer is not applied.

This for example causes the consumer to process mV when expecting uV.
Make sure to always apply the scaling factor requested by the consumer.

Fixes: adc8ec5ff183 ("iio: inkern: pass through raw values if no scaling")
Signed-off-by: Liam Beguin <liambeguin@gmail.com>
Reviewed-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220108205319.2046348-3-liambeguin@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index bfdac32b85527348d18ec9d57698701010a5fda8..ad6c581ab2169e6241e86a6274b5f34295bab682 100644 (file)
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -600,10 +600,10 @@ static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
                                        IIO_CHAN_INFO_SCALE);
        if (scale_type < 0) {
                /*
-                * Just pass raw values as processed if no scaling is
-                * available.
+                * If no channel scaling is available apply consumer scale to
+                * raw value and return.
                 */
-               *processed = raw;
+               *processed = raw * scale;
                return 0;
        }