linux-kernel - Re: [PATCH -next v2] usb: musb: Do not check 0 for platform_get_irq

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Date:   Thu, 3 Aug 2023 14:41:13 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...il.com>
To:     Zhu Wang <wangzhu9@...wei.com>, b-liu@...com,
        gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next v2] usb: musb: Do not check 0 for
 platform_get_irq_byname()

On 8/3/23 2:31 PM, Zhu Wang wrote:

> When platform_get_irq_byname() is called to get a interrupt number, it
> may return -EINVAL or -ENXIO when failed, while current code returned

   You still don't mention -EPROBE_DEFER. Propagating it upstream is
the _main_ reason we must not override what platform_get_irq_byname()
returns!

> -ENODEV, so we replace it with the return value of
> platform_get_irq_byname(). And we found that platform_get_irq_byname()
> never returned zero by reading its code.

   It used to return 0 (as both IRQ0 and the error indication).
Historically, there were several patches fixing the inconsistencies...

> Commit ce753ad1549c ("platform: finally disallow IRQ0 in
> platform_get_irq() and its ilk") makes sure IRQ0 is not returned.
> 
> Signed-off-by: Zhu Wang <wangzhu9@...wei.com>
> 
> ---
> Changes in v2:
> - Update the commit message, present the reason of replacing the return
> value of the probe.
> ---
>  drivers/usb/musb/musb_core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
> index ecbd3784bec3..b24adb5b399f 100644
> --- a/drivers/usb/musb/musb_core.c
> +++ b/drivers/usb/musb/musb_core.c
> @@ -2610,8 +2610,8 @@ static int musb_probe(struct platform_device *pdev)
>  	int		irq = platform_get_irq_byname(pdev, "mc");
>  	void __iomem	*base;
>  
> -	if (irq <= 0)
> -		return -ENODEV;
> +	if (irq < 0)
> +		return irq;
>  
>  	base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(base))
>