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Subject: Re: [PATCH] slimbus: qcom: Fix IRQ check in qcom_slim_probe
To:     Miaoqian Lin <linmq006@gmail.com>, Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sagar Dharia <sdharia@codeaurora.org>,
        linux-arm-msm@vger.kernel.org, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org
References: <20220114061830.13456-1-linmq006@gmail.com>
From:   Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Message-ID: <239c3b32-6754-02ba-6bfd-7f05fa2adfed@linux.intel.com>
Date:   Fri, 14 Jan 2022 09:14:58 -0600
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On 1/14/22 12:18 AM, Miaoqian Lin wrote:
> platform_get_irq() returns negative error number instead 0 on failure.

the 'instead of' wording is a bit misleading:

platform_get_irq() returns non-zero IRQ number on success, negative
error number on failure. Zero is not a valid return valid.


> And the doc of platform_get_irq() provides a usage example:
> 
>     int irq = platform_get_irq(pdev, 0);
>     if (irq < 0)
>         return irq;
> 
> Fix the check of return value to catch errors correctly.
> 
> Fixes: ad7fcbc308b0 ("slimbus: qcom: Add Qualcomm Slimbus controller driver")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
> ---
>  drivers/slimbus/qcom-ctrl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/slimbus/qcom-ctrl.c b/drivers/slimbus/qcom-ctrl.c
> index f04b961b96cd..ec58091fc948 100644
> --- a/drivers/slimbus/qcom-ctrl.c
> +++ b/drivers/slimbus/qcom-ctrl.c
> @@ -510,9 +510,9 @@ static int qcom_slim_probe(struct platform_device *pdev)
>  	}
>  
>  	ctrl->irq = platform_get_irq(pdev, 0);
> -	if (!ctrl->irq) {
> +	if (ctrl->irq < 0) {
>  		dev_err(&pdev->dev, "no slimbus IRQ\n");
> -		return -ENODEV;
> +		return ctrl->irq;
>  	}
>  
>  	sctrl = &ctrl->ctrl;
>