linux-kernel - Re: [PATCH V14 14/15] irqchip / ACPI: Introduce ACPI_IRQ_MODEL

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Date:   Thu, 07 Jul 2022 13:59:02 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Jianmin Lv <lvjianmin@...ngson.cn>
Cc:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        Hanjun Guo <guohanjun@...wei.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhuacai@...ngson.cn>
Subject: Re: [PATCH V14 14/15] irqchip / ACPI: Introduce ACPI_IRQ_MODEL_LPIC for LoongArch

On Sun, 03 Jul 2022 09:45:31 +0100,
Jianmin Lv <lvjianmin@...ngson.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@...ngson.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.

	M.

-- 
Without deviation from the norm, progress is not possible.