linux-kernel - Re: [PATCH] driver-core: platform: Avoid to return IRQ 0 in platform_get

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Date:   Tue, 5 Dec 2017 10:20:03 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Arvind Yadav <arvind.yadav.cs@...il.com>
Cc:     gregkh@...uxfoundation.org, davem@...emloft.net,
        linus.walleij@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] driver-core: platform: Avoid to return IRQ 0 in
 platform_get_irq()

On Tue, Dec 05, 2017 at 11:41:52PM +0530, Arvind Yadav wrote:
> Function platform_get_irq() can return 0. Which means NO_IRQ.
> So this change will not allow to return 0.
> 
> This change is help to use platform_get_irq() without this,
> 
> 	val = platform_get_irq();
> 	if (val <= 0)
> 		ret = val ? val : -ENODEV;
> 
> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>

You need to audit the drivers and make sure you are not breaking them
with this. I believe at least i2c designware controller on certain
boards has DEFINE_RES_IRQ(0) which will be broken by this patch.

> ---
>  drivers/base/platform.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index c203fb9..7b3079c 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -127,7 +127,7 @@ int platform_get_irq(struct platform_device *dev, unsigned int num)
>  		irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
>  	}
>  
> -	return r ? r->start : -ENXIO;
> +	return r && r->start ? r->start : -ENXIO;
>  #endif
>  }
>  EXPORT_SYMBOL_GPL(platform_get_irq);
> -- 
> 2.7.4
> 

Thanks.

-- 
Dmitry