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Subject: Re: [PATCH V4 1/4] ACPI / PCI: fix LPIC IRQ model default PCI IRQ
 polarity
To:     Bjorn Helgaas <helgaas@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>, linux-kernel@vger.kernel.org,
        loongarch@lists.linux.dev, Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Huacai Chen <chenhuacai@loongson.cn>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Len Brown <lenb@kernel.org>, rafael@kernel.org,
        linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org
References: <20221021120129.GA185586@bhelgaas>
From:   Jianmin Lv <lvjianmin@loongson.cn>
Message-ID: <8362ab48-7769-8139-8ca9-aca75147a853@loongson.cn>
Date:   Sat, 22 Oct 2022 10:05:40 +0800
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On 2022/10/21 下午8:01, Bjorn Helgaas wrote:
> On Fri, Oct 21, 2022 at 09:58:57AM +0800, Jianmin Lv wrote:
>> On 2022/10/21 上午12:47, Bjorn Helgaas wrote:
>>> On Thu, Oct 20, 2022 at 04:22:02PM +0800, Jianmin Lv wrote:
>>>> On LoongArch ACPI based systems, the PCI devices (e.g. sata
>>>> controlers and PCI-to-to PCI bridge controlers) existed in
>>>> Loongson chipsets output high-level interrupt signal to the
>>>> interrupt controller they connected to,
> 
>>> The point is that one should be able to write this code from a spec,
>>> without having to empirically discover the interrupt polarity.  What
>>> spec tells you about using ACTIVE_HIGH here?
>>>
>> Yes, no mentions for the inverter in ACPI spec, the description about
>> device interrupt type can be found in Loongson chipset manual:
>>
>> https://github.com/loongson/LoongArch-Documentation/blob/main/docs/Loongson-7A1000-usermanual-EN/interrupt-controller/device-interrupt-types.adoc
> 
> That's the kind of reference I was looking for.  The link to HTML is
> convenient in some ways, but since specs evolve over time and URLs are
> ephemeral, I think a citation like "Loongson 7A1000 Bridge User Manual
> v2.00, sec 5.3" is more likely to be useful far in the future.
> 
Ok, good suggestion, thanks.

> Bjorn
>