linux-kernel - Re: [PATCH 01/10 v4] Input: ep93xx_keypad: Fix platform_get

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Message-ID: <20171120162941.GD31757@n2100.armlinux.org.uk>
Date:   Mon, 20 Nov 2017 16:29:42 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Arvind Yadav <arvind.yadav.cs@...il.com>
Cc:     dmitry.torokhov@...il.com, maxime.ripard@...e-electrons.com,
        wens@...e.org, mcuos.com@...il.com, linux@...ck-us.net,
        lee.jones@...aro.org, linux-kernel@...r.kernel.org,
        linux-input@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 01/10 v4] Input: ep93xx_keypad: Fix platform_get_irq's
 error checking

On Mon, Nov 20, 2017 at 09:56:21PM +0530, Arvind Yadav wrote:
> The platform_get_irq() function returns negative if an error occurs.
> zero or positive number on success. platform_get_irq() error checking
> for zero is not correct.
> 
> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
> ---
> changes in v2 :
>               Return keypad->irq insted of -ENXIO.
> changes in v3 :
>               Add failure case '<= 0' instead of '< 0'. IRQ0 is not valid.
> changes ib v4 :
>               Return -ENXIO insted of keypad->irq. Which was not correct in v3.
> 
>  drivers/input/keyboard/ep93xx_keypad.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/keyboard/ep93xx_keypad.c b/drivers/input/keyboard/ep93xx_keypad.c
> index f77b295..c6eb31a 100644
> --- a/drivers/input/keyboard/ep93xx_keypad.c
> +++ b/drivers/input/keyboard/ep93xx_keypad.c
> @@ -257,7 +257,7 @@ static int ep93xx_keypad_probe(struct platform_device *pdev)
>  	}
>  
>  	keypad->irq = platform_get_irq(pdev, 0);
> -	if (!keypad->irq) {
> +	if (keypad->irq <= 0) {
>  		err = -ENXIO;

Still not right.

		err = keypad->irq < 0 ? keypad->irq : -ENXIO;

would have the right effect.

However, I disagree with the idea of making platform_get_irq() return
an error if there is a zero irq specified as suggested in a previous
review - zero means "not present" and that is not necessarily an error -
it's up to the driver to decide whether it can proceed without an
interrupt, or whether it should error out on the probe function.

-- 
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