iio: hx711: fix bug in reset functionality

Return value in hx711_reset() should indicate status of dout otherwise the
calling function is reporting an error as false positive

If there are two reads too close to each other, then the second one will
never succeed. This happens especially when using buffered mode with both
channels enabled.

When changing the channel on every trigger event the former 100 ms are not
enough for waiting until the device indicates normal mode.

Wait up to 1 second until the device turns into normal mode.

Signed-off-by: Andreas Klinger <ak@it-klinger.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index a38162ee7dcb37c5c5716659d4b8a67763e8dd22..9430b54121e002a9985879bf489f48fbd3c3e798 100644 (file)
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -153,15 +153,16 @@ static int hx711_wait_for_ready(struct hx711_data *hx711_data)
        int i, val;
 
        /*
-        * a maximum reset cycle time of 56 ms was measured.
-        * we round it up to 100 ms
+        * in some rare cases the reset takes quite a long time
+        * especially when the channel is changed.
+        * Allow up to one second for it
         */
        for (i = 0; i < 100; i++) {
                val = gpiod_get_value(hx711_data->gpiod_dout);
                if (!val)
                        break;
-               /* sleep at least 1 ms */
-               msleep(1);
+               /* sleep at least 10 ms */
+               msleep(10);
        }
        if (val)
                return -EIO;
@@ -203,9 +204,7 @@ static int hx711_reset(struct hx711_data *hx711_data)
                 * after a dummy read we need to wait vor readiness
                 * for not mixing gain pulses with the clock
                 */
-               ret = hx711_wait_for_ready(hx711_data);
-               if (ret)
-                       return ret;
+               val = hx711_wait_for_ready(hx711_data);
        }
 
        return val;