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Message-ID: <32ecbd1c-0940-85ee-2ca9-687d80317948@arm.com>
Date:   Thu, 6 Oct 2022 11:34:38 +0100
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Subject: Re: [PATCH] iommu: fsl_pamu: Replace NO_IRQ by 0
Content-Language: en-GB
To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>
Cc:     linux-kernel@vger.kernel.org, iommu@lists.linux.dev
References: <2a2570a8d12c80a7d36837b6c586daa708ca09d7.1665033732.git.christophe.leroy@csgroup.eu>
From:   Robin Murphy <robin.murphy@arm.com>
In-Reply-To: <2a2570a8d12c80a7d36837b6c586daa708ca09d7.1665033732.git.christophe.leroy@csgroup.eu>
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On 2022-10-06 06:24, Christophe Leroy wrote:
> NO_IRQ is used to check the return of irq_of_parse_and_map().
> 
> On some architecture NO_IRQ is 0, on other architectures it is -1.
> 
> irq_of_parse_and_map() returns 0 on error, independent of NO_IRQ.
> 
> So use 0 instead of using NO_IRQ.

Crucially, NO_IRQ *is* 0 on PowerPC where this driver actually runs, so 
there's no functional issue here. However the justification for cleaning 
it up makes perfect sense overall.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
>   drivers/iommu/fsl_pamu.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/fsl_pamu.c b/drivers/iommu/fsl_pamu.c
> index 0d03f837a5d4..1b53d2da2c19 100644
> --- a/drivers/iommu/fsl_pamu.c
> +++ b/drivers/iommu/fsl_pamu.c
> @@ -779,7 +779,7 @@ static int fsl_pamu_probe(struct platform_device *pdev)
>   	of_get_address(dev->of_node, 0, &size, NULL);
>   
>   	irq = irq_of_parse_and_map(dev->of_node, 0);
> -	if (irq == NO_IRQ) {
> +	if (!irq) {
>   		dev_warn(dev, "no interrupts listed in PAMU node\n");
>   		goto error;
>   	}
> @@ -903,7 +903,7 @@ static int fsl_pamu_probe(struct platform_device *pdev)
>   	return 0;
>   
>   error:
> -	if (irq != NO_IRQ)
> +	if (irq)
>   		free_irq(irq, data);
>   
>   	kfree_sensitive(data);