[PATCH] iio: adc: meson_saradc: Better handle BL30 not releaseing the hardware

* [PATCH] iio: adc: meson_saradc: Better handle BL30 not releaseing the hardware
@ 2023-02-16 14:07 ` Uwe Kleine-König
  0 siblings, 0 replies; 6+ messages in thread
From: Uwe Kleine-König @ 2023-02-16 14:07 UTC (permalink / raw)
  To: Jonathan Cameron, Neil Armstrong, Kevin Hilman, Jerome Brunet,
	Martin Blumenstingl, Andy Shevchenko, Nuno Sá,
	linux-iio, linux-arm-kernel, linux-amlogic, kernel
  Cc: Lars-Peter Clausen

meson_sar_adc_lock() might return an error if BL30 doesn't release its
lock on the hardware. Just returning early from .remove() is wrong
however as this keeps the clocks and regulators on which is never
cleaned up later.

So only skip hardware accesses with an error message if
meson_sar_adc_lock() fails, but disable clocks and regulator and return
zero to suppress another error message by the driver core.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
Hello,

maybe someone with more hardware specific knowledge can improve the
procedure here. Maybe some HW access is fine even without the lock to
quiescent it, or maybe the lock can be dropped completely? Or the
ordering can be changed to reduce the number of if blocks.

Best regards
Uwe

 drivers/iio/adc/meson_saradc.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
index 85b6826cc10c..636fee27b6b2 100644
--- a/drivers/iio/adc/meson_saradc.c
+++ b/drivers/iio/adc/meson_saradc.c
@@ -957,29 +957,30 @@ static int meson_sar_adc_hw_enable(struct iio_dev *indio_dev)
 	return ret;
 }
 
-static int meson_sar_adc_hw_disable(struct iio_dev *indio_dev)
+static void meson_sar_adc_hw_disable(struct iio_dev *indio_dev)
 {
 	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
 	int ret;
 
 	ret = meson_sar_adc_lock(indio_dev);
 	if (ret)
-		return ret;
+		dev_err(indio_dev->dev.parent, "Failed to lock ADC (%pE)\n", ERR_PTR(ret));
 
 	clk_disable_unprepare(priv->adc_clk);
 
-	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
-			   MESON_SAR_ADC_REG3_ADC_EN, 0);
+	if (!ret) {
+		regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
+				   MESON_SAR_ADC_REG3_ADC_EN, 0);
 
-	meson_sar_adc_set_bandgap(indio_dev, false);
+		meson_sar_adc_set_bandgap(indio_dev, false);
+	}
 
 	clk_disable_unprepare(priv->core_clk);
 
 	regulator_disable(priv->vref);
 
-	meson_sar_adc_unlock(indio_dev);
-
-	return 0;
+	if (!ret)
+		meson_sar_adc_unlock(indio_dev);
 }
 
 static irqreturn_t meson_sar_adc_irq(int irq, void *data)
@@ -1283,7 +1284,9 @@ static int meson_sar_adc_remove(struct platform_device *pdev)
 
 	iio_device_unregister(indio_dev);
 
-	return meson_sar_adc_hw_disable(indio_dev);
+	meson_sar_adc_hw_disable(indio_dev);
+
+	return 0;
 }
 
 static int meson_sar_adc_suspend(struct device *dev)

base-commit: 1b929c02afd37871d5afb9d498426f83432e71c2
-- 
2.39.1


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