Re: [PATCH v2] mmc: sdhci-of-dwcmshc: check bus clock enable result in the, probe() method

[Adrian Hunter <adrian.hunter@intel.com>]

On 29/05/2026 23:28, Sergey Shtylyov wrote:
> In the driver's probe() method, clk_disable_unprepare() for the bus clock
> is called on the error path even if the prior clk_prepare_enable() call has
> failed (and the same thing happens in the remove() method as well) -- that
> would cause the prepare/enable counter imbalance.  Also, the same problem
> can happen in the driver's suspend() method; note that the resume() method
> does check the clk_prepare_enable()'s result -- let's be consistent and do
> that in probe() method as well.  BTW, I don't know for sure what does the
> bus clock control -- if it affects the register accesses, the driver will
> likely to cause (e.g. on ARM) a kernel oops if it fails to prepare/enable
> the bus clock in the probe() method...
> 
> Found by Linux Verification Center (linuxtesting.org) with the Svace static
> analysis tool.
> 
> Fixes: e438cf49b305 ("mmc: sdhci-of-dwcmshc: add SDHCI OF Synopsys DWC MSHC driver")
> Fixes: bccce2ec7790 ("mmc: sdhci-of-dwcmshc: add suspend/resume support")
> Signed-off-by: Sergey Shtylyov <s.shtylyov@auroraos.dev>

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> 
> ---
> This patch is against the fixes branch of Ulf Hansson's mmc.git repo.
> 
> Changes in version 2:
> - mentioned the problem in the remove() method as well, somewhat rephrased
>   the patch description.
> 
>  drivers/mmc/host/sdhci-of-dwcmshc.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index b9ecd91f44ad..29af07561a86 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -2441,13 +2441,16 @@ static int dwcmshc_probe(struct platform_device *pdev)
>  			return err;
>  
>  		priv->bus_clk = devm_clk_get(dev, "bus");
> -		if (!IS_ERR(priv->bus_clk))
> -			clk_prepare_enable(priv->bus_clk);
> +		if (!IS_ERR(priv->bus_clk)) {
> +			err = clk_prepare_enable(priv->bus_clk);
> +			if (err)
> +				goto err_clk;
> +		}
>  	}
>  
>  	err = mmc_of_parse(host->mmc);
>  	if (err)
> -		goto err_clk;
> +		goto err_bus_clk;
>  
>  	sdhci_get_of_property(pdev);
>  
> @@ -2461,7 +2464,7 @@ static int dwcmshc_probe(struct platform_device *pdev)
>  	if (pltfm_data->init) {
>  		err = pltfm_data->init(&pdev->dev, host, priv);
>  		if (err)
> -			goto err_clk;
> +			goto err_bus_clk;
>  	}
>  
>  #ifdef CONFIG_ACPI
> @@ -2507,9 +2510,10 @@ static int dwcmshc_probe(struct platform_device *pdev)
>  err_rpm:
>  	pm_runtime_disable(dev);
>  	pm_runtime_put_noidle(dev);
> +err_bus_clk:
> +	clk_disable_unprepare(priv->bus_clk);
>  err_clk:
>  	clk_disable_unprepare(pltfm_host->clk);
> -	clk_disable_unprepare(priv->bus_clk);
>  	clk_bulk_disable_unprepare(priv->num_other_clks, priv->other_clks);
>  	return err;
>  }