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Subject: Re: [PATCH V14 14/15] irqchip / ACPI: Introduce ACPI_IRQ_MODEL_LPIC
 for LoongArch
From:   Jianmin Lv <lvjianmin@loongson.cn>
To:     Marc Zyngier <maz@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        Hanjun Guo <guohanjun@huawei.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Huacai Chen <chenhuacai@loongson.cn>
References: <1656837932-18257-1-git-send-email-lvjianmin@loongson.cn>
 <1656837932-18257-15-git-send-email-lvjianmin@loongson.cn>
 <87y1x5krjd.wl-maz@kernel.org>
 <f76927be-8c8c-5bbe-ef5c-a63f4a09b29c@loongson.cn>
Message-ID: <bfbd08d6-6f09-3ddb-0fdf-8c459352cf0f@loongson.cn>
Date:   Thu, 14 Jul 2022 18:02:54 +0800
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On 2022/7/8 上午11:17, Jianmin Lv wrote:
> 
> 
> On 2022/7/7 下午8:59, Marc Zyngier wrote:
>> On Sun, 03 Jul 2022 09:45:31 +0100,
>> Jianmin Lv <lvjianmin@loongson.cn> wrote:
>>>
>>> For LoongArch, ACPI_IRQ_MODEL_LPIC is introduced, and then the
>>> callback acpi_get_gsi_domain_id and acpi_gsi_to_irq_fallback are
>>> implemented.
>>>
>>> The acpi_get_gsi_domain_id callback returns related fwnode handle
>>> of irqdomain for different GSI range.
>>>
>>> The acpi_gsi_to_irq_fallback will create new mapping for gsi when
>>> the mapping of it is not found.
>>>
>>> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
>>> ---
>>>   drivers/acpi/bus.c                  |  3 +++
>>>   drivers/irqchip/irq-loongarch-cpu.c | 37 
>>> +++++++++++++++++++++++++++++++++++++
>>>   include/linux/acpi.h                |  1 +
>>>   3 files changed, 41 insertions(+)
>>>
>>> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
>>> index 86fa61a..63fbf00 100644
>>> --- a/drivers/acpi/bus.c
>>> +++ b/drivers/acpi/bus.c
>>> @@ -1145,6 +1145,9 @@ static int __init acpi_bus_init_irq(void)
>>>       case ACPI_IRQ_MODEL_PLATFORM:
>>>           message = "platform specific model";
>>>           break;
>>> +    case ACPI_IRQ_MODEL_LPIC:
>>> +        message = "LPIC";
>>> +        break;
>>>       default:
>>>           pr_info("Unknown interrupt routing model\n");
>>>           return -ENODEV;
>>> diff --git a/drivers/irqchip/irq-loongarch-cpu.c 
>>> b/drivers/irqchip/irq-loongarch-cpu.c
>>> index c2f7411..1b241d7 100644
>>> --- a/drivers/irqchip/irq-loongarch-cpu.c
>>> +++ b/drivers/irqchip/irq-loongarch-cpu.c
>>> @@ -15,6 +15,41 @@
>>>   static struct irq_domain *irq_domain;
>>> +static int lpic_gsi_to_irq(u32 gsi)
>>> +{
>>> +    /* Only pch irqdomain transferring is required for LoongArch. */
>>> +    if (gsi >= GSI_MIN_PCH_IRQ && gsi <= GSI_MAX_PCH_IRQ)
>>> +        return acpi_register_gsi(NULL, gsi, ACPI_LEVEL_SENSITIVE, 
>>> ACPI_ACTIVE_HIGH);
>>> +    return -1;
>>
>> The expected return value on failure is 0 (which indicates that no
>> interrupt was mapped). Here, things will break as acpi_gsi_to_irq()
>> stores the result as unsigned, and compares the result to 0.
>>
> 
> Ok, thanks, I'll change the return value to 0 on failure and change 
> return type to unsigned int.
> 
> 

Hi, Marc, if the return type is changed to unsigned int, the return type 
of the fallback handler in the patch:
ACPI: irq: Allow acpi_gsi_to_irq() to have an arch-specific fallback

should be changed to unsigned int too, yes?

>>     M.
>>