[PATCH v2 10/10] iio: adc: ad7606: Disable PWM usage for non backend version

[Guillaume Stols <gstols@baylibre.com>]

Since the pwm was introduced before backend, there was an example use
whit triggered buffers. However, using it may be dangerous, because if
the PWM goes too fast, a new conversion can be triggered before the
transmission is over, whit the associated mess in the buffers.
Until a solution is found to mitigate this risk, for instante CRC
support, the PWM will be disabled.

Signed-off-by: Guillaume Stols <gstols@baylibre.com>
---
 drivers/iio/adc/ad7606.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index f710445bdc22..0c12ca237ee9 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -599,7 +599,6 @@ static int ad7606_buffer_postenable(struct iio_dev *indio_dev)
 	struct ad7606_state *st = iio_priv(indio_dev);
 
 	gpiod_set_value(st->gpio_convst, 1);
-	ad7606_pwm_set_swing(st);
 
 	return 0;
 }
@@ -609,7 +608,6 @@ static int ad7606_buffer_predisable(struct iio_dev *indio_dev)
 	struct ad7606_state *st = iio_priv(indio_dev);
 
 	gpiod_set_value(st->gpio_convst, 0);
-	ad7606_pwm_set_low(st);
 
 	return 0;
 }
@@ -838,6 +836,12 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
 		indio_dev->setup_ops = &ad7606_pwm_buffer_ops;
 	} else {
 		init_completion(&st->completion);
+
+		/* Reserve the PWM use only for backend (force gpio_convst definition) */
+		if (!st->gpio_convst)
+			return dev_err_probe(dev, -EINVAL,
+					     "No backend, connect convst to a GPIO");
+
 		ret = devm_request_threaded_irq(dev, irq,
 						NULL,
 						&ad7606_interrupt,

-- 
2.34.1