linux-kernel - RE: [PATCH v3 2/6] irqchip: Add interrupt controller support for Realtek DHC SoCs

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Message-ID: <d9dad6be6ee14b77910e95dd2571c828@realtek.com>
Date:   Mon, 11 Dec 2023 05:19:55 +0000
From:   James Tai [戴志峰] <james.tai@...ltek.com>
To:     Rob Herring <robh@...nel.org>,
        Dan Carpenter <dan.carpenter@...aro.org>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        kernel test robot <lkp@...el.com>,
        "Dan Carpenter" <error27@...il.com>
Subject: RE: [PATCH v3 2/6] irqchip: Add interrupt controller support for Realtek DHC SoCs

Hi Rob,

>
>On Wed, Nov 29, 2023 at 11:21:06AM +0300, Dan Carpenter wrote:
>> On Wed, Nov 29, 2023 at 01:43:35PM +0800, James Tai wrote:
>> > +static int realtek_intc_subset(struct device_node *node, struct
>> > +realtek_intc_data *data, int index) {
>> > +   struct realtek_intc_subset_data *subset_data =
>&data->subset_data[index];
>> > +   const struct realtek_intc_subset_cfg *cfg = &data->info->cfg[index];
>> > +   int irq;
>> > +
>> > +   irq = irq_of_parse_and_map(node, index);
>> > +   if (irq <= 0)
>> > +           return irq;
>>
>> I don't think irq_of_parse_and_map() can return negatives.  Only zero
>> on error.  Returning zero on error is a historical artifact with IRQ
>> functions and a constant source of bugs.  But here returning zero is
>> success.  See my blog for more details:
>> https://staticthinking.wordpress.com/2023/08/07/writing-a-check-for-ze
>> ro-irq-error-codes/
>
>It's worse than that. The irq functions historically returned NO_IRQ on error, but
>that could be 0 or -1 depending on the arch.
>
>Use of_irq_get() instead. It's a bit better in that it returns an error code for most
>cases. But still returns 0 on mapping failure.
>

I will use of_irq_get() instead and adjust the return value of realtek_intc_subset() in the next patches.

Thanks for your feedback.

Regards,
James