[PATCH v2 3/5] iio: adc: ad7625: fix sampling frequency handling

[Nicolae-Daniel Deaconescu]

Fix the following issues in the handling of the sampling frequency:

- Fix the issue where writing 0 to sampling_frequency caused a division
  by zero. Return -EINVAL instead.
- Fix the issue where a waveform that the PWM had to round up was not
  reported as an error. pwm_round_waveform_might_sleep() returns 1 in that
  case and ad7625_set_sampling_freq() passed it on, so the write to
  sampling_frequency returned 1 and the new waveforms were dropped. Return
  -EINVAL instead.
- Fix the issue where probe() went on after failing to set the initial
  sampling frequency. The result of dev_err_probe() was not returned, so
  the PWMs stayed unconfigured. Return the error.

Fixes: b7ffd0fa65e9 ("iio: adc: ad7625: add driver")
Signed-off-by: Nicolae-Daniel Deaconescu <Nicolae-daniel.Deaconescu@xxxxxxxxxx>
---
 drivers/iio/adc/ad7625.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/adc/ad7625.c b/drivers/iio/adc/ad7625.c
index e73a5c9e7f0b..0de7f29797ef 100644
--- a/drivers/iio/adc/ad7625.c
+++ b/drivers/iio/adc/ad7625.c
@@ -178,6 +178,9 @@ static int ad7625_set_sampling_freq(struct ad7625_state *st, u32 freq)
 	unsigned long target;
 	int ret;
 
+	if (!freq)
+		return -EINVAL;
+
 	target = DIV_ROUND_UP(NSEC_PER_SEC, freq);
 	cnv_wf.period_length_ns = clamp(target, 100UL, 10UL * NSEC_PER_USEC);
 
@@ -189,7 +192,7 @@ static int ad7625_set_sampling_freq(struct ad7625_state *st, u32 freq)
 
 	ret = pwm_round_waveform_might_sleep(st->cnv_pwm, &cnv_wf);
 	if (ret)
-		return ret;
+		return ret < 0 ? ret : -EINVAL;
 
 	/*
 	 * Set up the burst signal for transferring data. period and
@@ -206,7 +209,7 @@ static int ad7625_set_sampling_freq(struct ad7625_state *st, u32 freq)
 
 	ret = pwm_round_waveform_might_sleep(st->clk_gate_pwm, &clk_gate_wf);
 	if (ret)
-		return ret;
+		return ret < 0 ? ret : -EINVAL;
 
 	st->cnv_wf = cnv_wf;
 	st->clk_gate_wf = clk_gate_wf;
@@ -646,8 +649,8 @@ static int ad7625_probe(struct platform_device *pdev)
 
 	ret = ad7625_set_sampling_freq(st, default_sample_freq);
 	if (ret)
-		dev_err_probe(dev, ret,
-			      "failed to set valid sampling frequency\n");
+		return dev_err_probe(dev, ret,
+				     "failed to set valid sampling frequency\n");
 
 	return devm_iio_device_register(dev, indio_dev);
 }
-- 
2.34.1