[{"id":3679389,"web_url":"http://patchwork.ozlabs.org/comment/3679389/","msgid":"<20260420132838.147d18b6@jic23-huawei>","list_archive_url":null,"date":"2026-04-20T12:28:38","subject":"Re: [PATCH v3] iio: adc: npcm: fix unbalanced\n clk_disable_unprepare()","submitter":{"id":10151,"url":"http://patchwork.ozlabs.org/api/people/10151/","name":"Jonathan Cameron","email":"jic23@kernel.org"},"content":"On Tue, 14 Apr 2026 13:30:06 +0100\nDavid Carlier wrote:\n\n> The driver acquired the ADC clock with devm_clk_get() and read its\n> rate, but never called clk_prepare_enable(). The probe error path and\n> npcm_adc_remove() both called clk_disable_unprepare() unconditionally,\n> causing the clk framework's enable/prepare counts to underflow on\n> probe failure or module unbind.\n> \n> The issue went unnoticed because NPCM BMC firmware leaves the ADC\n> clock enabled at boot, so the driver happened to work in practice.\n> \n> Switch to devm_clk_get_enabled() so the clock is properly enabled\n> during probe and automatically released by the device-managed\n> cleanup, and drop the now-redundant clk_disable_unprepare() from\n> both the probe error path and remove().\n> \n> While at it, drop the duplicate error message on devm_request_irq()\n> failure since the IRQ core already logs it.\n> \n> Fixes: 9bf85fbc9d8f (\"iio: adc: add NPCM ADC driver\")\n> Signed-off-by: David Carlier \n> Reviewed-by: Andy Shevchenko \nApplied to the fixes-togreg branch of iio.git. Note I'll rebase that on rc1\nonce available, before sending a pull request.\n\nThanks,\n\nJonathan\n\n> ---\n> v3: mention the dev_err drop in the commit log and collapse the\n> single-statement -ENODEV branch (Andy Shevchenko).\n> v2: drop redundant dev_err() on devm_request_irq() failure since the\n> IRQ core already logs it, and remove the now-single-statement\n> braces (Andy Shevchenko).\n> \n> drivers/iio/adc/npcm_adc.c | 25 ++++++++-----------------\n> 1 file changed, 8 insertions(+), 17 deletions(-)\n> \n> diff --git a/drivers/iio/adc/npcm_adc.c b/drivers/iio/adc/npcm_adc.c\n> index ddabb9600d46..61c8b825bda1 100644\n> --- a/drivers/iio/adc/npcm_adc.c\n> +++ b/drivers/iio/adc/npcm_adc.c\n> @@ -231,7 +231,7 @@ static int npcm_adc_probe(struct platform_device *pdev)\n> \tif (IS_ERR(info->reset))\n> \t\treturn PTR_ERR(info->reset);\n> \n> -\tinfo->adc_clk = devm_clk_get(&pdev->dev, NULL);\n> +\tinfo->adc_clk = devm_clk_get_enabled(&pdev->dev, NULL);\n> \tif (IS_ERR(info->adc_clk)) {\n> \t\tdev_warn(&pdev->dev, \"ADC clock failed: can't read clk\\n\");\n> \t\treturn PTR_ERR(info->adc_clk);\n> @@ -244,17 +244,13 @@ static int npcm_adc_probe(struct platform_device *pdev)\n> \tinfo->adc_sample_hz = clk_get_rate(info->adc_clk) / ((div + 1) * 2);\n> \n> \tirq = platform_get_irq(pdev, 0);\n> -\tif (irq < 0) {\n> -\t\tret = irq;\n> -\t\tgoto err_disable_clk;\n> -\t}\n> +\tif (irq < 0)\n> +\t\treturn irq;\n> \n> \tret = devm_request_irq(&pdev->dev, irq, npcm_adc_isr, 0,\n> \t\t\t \"NPCM_ADC\", indio_dev);\n> -\tif (ret < 0) {\n> -\t\tdev_err(dev, \"failed requesting interrupt\\n\");\n> -\t\tgoto err_disable_clk;\n> -\t}\n> +\tif (ret < 0)\n> +\t\treturn ret;\n> \n> \treg_con = ioread32(info->regs + NPCM_ADCCON);\n> \tinfo->vref = devm_regulator_get_optional(&pdev->dev, \"vref\");\n> @@ -262,7 +258,7 @@ static int npcm_adc_probe(struct platform_device *pdev)\n> \t\tret = regulator_enable(info->vref);\n> \t\tif (ret) {\n> \t\t\tdev_err(&pdev->dev, \"Can't enable ADC reference voltage\\n\");\n> -\t\t\tgoto err_disable_clk;\n> +\t\t\treturn ret;\n> \t\t}\n> \n> \t\tiowrite32(reg_con & ~NPCM_ADCCON_REFSEL,\n> @@ -272,10 +268,8 @@ static int npcm_adc_probe(struct platform_device *pdev)\n> \t\t * Any error which is not ENODEV indicates the regulator\n> \t\t * has been specified and so is a failure case.\n> \t\t */\n> -\t\tif (PTR_ERR(info->vref) != -ENODEV) {\n> -\t\t\tret = PTR_ERR(info->vref);\n> -\t\t\tgoto err_disable_clk;\n> -\t\t}\n> +\t\tif (PTR_ERR(info->vref) != -ENODEV)\n> +\t\t\treturn PTR_ERR(info->vref);\n> \n> \t\t/* Use internal reference */\n> \t\tiowrite32(reg_con | NPCM_ADCCON_REFSEL,\n> @@ -314,8 +308,6 @@ static int npcm_adc_probe(struct platform_device *pdev)\n> \tiowrite32(reg_con & ~NPCM_ADCCON_ADC_EN, info->regs + NPCM_ADCCON);\n> \tif (!IS_ERR(info->vref))\n> \t\tregulator_disable(info->vref);\n> -err_disable_clk:\n> -\tclk_disable_unprepare(info->adc_clk);\n> \n> \treturn ret;\n> }\n> @@ -332,7 +324,6 @@ static void npcm_adc_remove(struct platform_device *pdev)\n> \tiowrite32(regtemp & ~NPCM_ADCCON_ADC_EN, info->regs + NPCM_ADCCON);\n> \tif (!IS_ERR(info->vref))\n> \t\tregulator_disable(info->vref);\n> -\tclk_disable_unprepare(info->adc_clk);\n> }\n> \n> static struct platform_driver npcm_adc_driver = {","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","openbmc@lists.ozlabs.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=b03Nikmd;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=112.213.38.117; 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