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patch "iio: adc: npcm: fix unbalanced clk_disable_unprepare()" added to char-misc-linus

PATCH [email protected] 1 participant 1 message May 15

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Stable branch IIO Arm/nuvoton npcm architecture
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This is a note to let you know that I've just added the patch titled

iio: adc: npcm: fix unbalanced clk_disable_unprepare()

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 0d42e2c0bd6ceb89e44c6e065f9bdf9b1df3ef0c Mon Sep 17 00:00:00 2001
From: David Carlier <[email protected]>
Date: Tue, 14 Apr 2026 13:30:06 +0100
Subject: iio: adc: npcm: fix unbalanced clk_disable_unprepare()

The driver acquired the ADC clock with devm_clk_get() and read its rate, but never called clk_prepare_enable(). The probe error path and npcm_adc_remove() both called clk_disable_unprepare() unconditionally, causing the clk framework's enable/prepare counts to underflow on probe failure or module unbind.

The issue went unnoticed because NPCM BMC firmware leaves the ADC clock enabled at boot, so the driver happened to work in practice.

Switch to devm_clk_get_enabled() so the clock is properly enabled during probe and automatically released by the device-managed cleanup, and drop the now-redundant clk_disable_unprepare() from both the probe error path and remove().

While at it, drop the duplicate error message on devm_request_irq() failure since the IRQ core already logs it.

Fixes 9bf85fbc9d8f ("iio: adc: add NPCM ADC driver")
Signed-off-by David Carlier <[email protected]>
Reviewed-by Andy Shevchenko <[email protected]>
Cc <[email protected]>
Signed-off-by Jonathan Cameron <[email protected]>
---
 drivers/iio/adc/npcm_adc.c | 25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)
drivers/iio/adc/npcm_adc.c +8 -17
index ddabb9600d46..61c8b825bda1 100644
@@ -231,7 +231,7 @@ static int npcm_adc_probe(struct platform_device *pdev)
 	if (IS_ERR(info->reset))
 		return PTR_ERR(info->reset);
 
-	info->adc_clk = devm_clk_get(&pdev->dev, NULL);
+	info->adc_clk = devm_clk_get_enabled(&pdev->dev, NULL);
 	if (IS_ERR(info->adc_clk)) {
 		dev_warn(&pdev->dev, "ADC clock failed: can't read clk\n");
 		return PTR_ERR(info->adc_clk);

@@ -244,17 +244,13 @@ static int npcm_adc_probe(struct platform_device *pdev)
 	info->adc_sample_hz = clk_get_rate(info->adc_clk) / ((div + 1) * 2);
 
 	irq = platform_get_irq(pdev, 0);
-	if (irq < 0) {
-		ret = irq;
-		goto err_disable_clk;
-	}
+	if (irq < 0)
+		return irq;
 
 	ret = devm_request_irq(&pdev->dev, irq, npcm_adc_isr, 0,
 			       "NPCM_ADC", indio_dev);
-	if (ret < 0) {
-		dev_err(dev, "failed requesting interrupt\n");
-		goto err_disable_clk;
-	}
+	if (ret < 0)
+		return ret;
 
 	reg_con = ioread32(info->regs + NPCM_ADCCON);
 	info->vref = devm_regulator_get_optional(&pdev->dev, "vref");

@@ -262,7 +258,7 @@ static int npcm_adc_probe(struct platform_device *pdev)
 		ret = regulator_enable(info->vref);
 		if (ret) {
 			dev_err(&pdev->dev, "Can't enable ADC reference voltage\n");
-			goto err_disable_clk;
+			return ret;
 		}
 
 		iowrite32(reg_con & ~NPCM_ADCCON_REFSEL,

@@ -272,10 +268,8 @@ static int npcm_adc_probe(struct platform_device *pdev)
 		 * Any error which is not ENODEV indicates the regulator
 		 * has been specified and so is a failure case.
 		 */
-		if (PTR_ERR(info->vref) != -ENODEV) {
-			ret = PTR_ERR(info->vref);
-			goto err_disable_clk;
-		}
+		if (PTR_ERR(info->vref) != -ENODEV)
+			return PTR_ERR(info->vref);
 
 		/* Use internal reference */
 		iowrite32(reg_con | NPCM_ADCCON_REFSEL,

@@ -314,8 +308,6 @@ static int npcm_adc_probe(struct platform_device *pdev)
 	iowrite32(reg_con & ~NPCM_ADCCON_ADC_EN, info->regs + NPCM_ADCCON);
 	if (!IS_ERR(info->vref))
 		regulator_disable(info->vref);
-err_disable_clk:
-	clk_disable_unprepare(info->adc_clk);
 
 	return ret;
 }

@@ -332,7 +324,6 @@ static void npcm_adc_remove(struct platform_device *pdev)
 	iowrite32(regtemp & ~NPCM_ADCCON_ADC_EN, info->regs + NPCM_ADCCON);
 	if (!IS_ERR(info->vref))
 		regulator_disable(info->vref);
-	clk_disable_unprepare(info->adc_clk);
 }
 
 static struct platform_driver npcm_adc_driver = {
Signature · 1 line
2.54.0