linux-kernel - Re: [PATCH RFC V2 02/10] irqchip: Add LoongArch CPU interrupt controller support

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Message-ID: <271863fe-ffa0-af5e-22f6-d1e8e89d91ae@loongson.cn>
Date:   Wed, 8 Jun 2022 16:55:58 +0800
From:   Jianmin Lv <lvjianmin@...ngson.cn>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Huacai Chen <chenhuacai@...il.com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        Hanjun Guo <guohanjun@...wei.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Subject: Re: [PATCH RFC V2 02/10] irqchip: Add LoongArch CPU interrupt
 controller support



On 2022/6/7 下午2:56, Marc Zyngier wrote:
> On Tue, 07 Jun 2022 04:41:22 +0100,
> Jianmin Lv <lvjianmin@...ngson.cn> wrote:
>>
>>
>> On 2022/6/6 下午6:02, Marc Zyngier wrote:
>>> + Lorenzo and Hanjun who maintain the ACPI irq code
>>>
>>> On Thu, 02 Jun 2022 04:16:30 +0100,
>>> Jianmin Lv <lvjianmin@...ngson.cn> wrote:
> 
> [...]
> 
>>>> I'm so sorry, I really don't find a way to reuse driver/acpi/irq.c
>>>> after my humble work.
>>> I don't think reimplementing ACPI is the solution. What could be a
>>> reasonable approach is a way to overload the retrieval of the
>>> acpi_gsi_domain_id fwnode with a GSI parameter.
>>>
>>> I hacked the following patch, which will give you an idea of what I
>>> have in mind (only compile-tested).
>>
>>
>> Hi, Marc, thanks so much for your patch. I have verified it on my
>> LoongArch machine and it works well.
>>
>>
>> BTW, in acpi_get_irq_source_fwhandle(), maybe
>> acpi_get_gsi_domain_id(ctx->index) is needed to changed to
>> acpi_get_gsi_domain_id(irq->interrupts[ctx->index])?
> 
> Yes, absolutely. Thanks for spotting it.
> 
>> I have another question, for LoongArch, acpi_isa_irq_to_gsi is
>> required to implemente, but no common version, do we need to
>> implemente an weak version in driver/acpi/irq.c as following?
>>
>>
>> int __weak acpi_isa_irq_to_gsi(unsigned int isa_irq, u32 *gsi)
>> {
>>          if (gsi)
>>                  *gsi = isa_irq;
>>          return 0;
>> }
> 
> Do you actually have CONFIG_ISA? In 2022? For a brand new architecture?
> 
> If you really have to, then this needs to be a bit more involved:
> 
> #ifdef CONFIG_ISA
> int __weak acpi_isa_irq_to_gsi(unsigned int isa_irq, u32 *gsi)
> {
> 	if (irq < nr_legacy_irqs()) {
> 		*gsi = isa_irq;
> 		return 0;
> 	}
> 
> 	return -1;
> }
> #endif
> 
> But I'd rather you get rid of any such legacy if this can be avoided.
> 

Thanks for your suggestion, I have confirmed that we don't need 
CONFIT_ISA for LoongArch, so acpi_isa_irq_to_gsi is not needed either.

>> I'll use the way you provided here to reuse driver/acpi/irq.c in next
>> version. How should I do next? Should I integrate your patch into my
>> next version or wait for you to merge it first?
> 
> Please pick up the patch (with the above fix), and use it as a prefix
> to your series. It needs to be reviewed by the relevant maintainers
> anyway.
> 

Ok, thanks, I'll add relevant maintainers to review for next version.

> Thanks,
> 
> 	M.
>