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Subject: Re: [PATCH V1 1/2] irqchip/loongson-pch-pic: Support to set irq type
 for ACPI path
To:     Marc Zyngier <maz@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>, 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>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>, linux-pci@vger.kernel.org,
        linux-acpi@vger.kernel.org
References: <1660615291-35409-1-git-send-email-lvjianmin@loongson.cn>
 <1660615291-35409-2-git-send-email-lvjianmin@loongson.cn>
 <86leq37duw.wl-maz@kernel.org>
From:   Jianmin Lv <lvjianmin@loongson.cn>
Message-ID: <71fc2d5b-fc3c-0a2d-65ce-df7d5bb26503@loongson.cn>
Date:   Thu, 29 Sep 2022 10:35:17 +0800
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On 2022/9/28 下午10:49, Marc Zyngier wrote:
> On Mon, 15 Aug 2022 22:01:30 -0400,
> Jianmin Lv <lvjianmin@loongson.cn> wrote:
>>
>> For ACPI path, the translate callback used IRQ_TYPE_NONE and ignored
>> the irq type in fwspec->param[1]. For supporting to set type for
>> irqs of the irqdomain, fwspec->param[1] should be used to get irq
>> type.
>>
>> On Loongson platform, the irq trigger type of PCI devices is
>> high level, so high level triggered type is inputed to acpi_register_gsi
>> when create irq mapping for PCI devices.
>>
>> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
>> ---
>>   drivers/acpi/pci_irq.c                 |  3 ++-
>>   drivers/irqchip/irq-loongson-pch-pic.c | 10 ++++++----
>>   2 files changed, 8 insertions(+), 5 deletions(-)
> 
> $ ./scripts/get_maintainer.pl drivers/acpi/pci_irq.c
> Bjorn Helgaas <bhelgaas@google.com> (supporter:PCI SUBSYSTEM)
> "Rafael J. Wysocki" <rafael@kernel.org> (supporter:ACPI)
> Len Brown <lenb@kernel.org> (reviewer:ACPI)
> linux-pci@vger.kernel.org (open list:PCI SUBSYSTEM)
> linux-acpi@vger.kernel.org (open list:ACPI)
> linux-kernel@vger.kernel.org (open list)
> 
> How about you start Cc-ing some of the relevant people?
> 
Ok, thanks, I'll cc relevant people list here.

>>
>> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
>> index 08e1577..34483b3 100644
>> --- a/drivers/acpi/pci_irq.c
>> +++ b/drivers/acpi/pci_irq.c
>> @@ -393,7 +393,8 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
>>   	 * controller and must therefore be considered active high
>>   	 * as default.
>>   	 */
>> -	int polarity = acpi_irq_model == ACPI_IRQ_MODEL_GIC ?
>> +	int polarity = acpi_irq_model == ACPI_IRQ_MODEL_GIC ||
>> +		       acpi_irq_model == ACPI_IRQ_MODEL_LPIC ?
>>   				      ACPI_ACTIVE_HIGH : ACPI_ACTIVE_LOW;
> 
> The comment just above this only talks about ARM. Should it be
> updated? 

Ok, I'll update the comment.


Is this a limitation of the underlying interrupt controller?
> 
It's the limitation that pci interrupt source of LoongArch only sends 
high level trigger signal to interrupt controller(though, pci spec 
requires asserted low).


>>   	char *link = NULL;
>>   	char link_desc[16];
>> diff --git a/drivers/irqchip/irq-loongson-pch-pic.c b/drivers/irqchip/irq-loongson-pch-pic.c
>> index b6f1392..5067010 100644
>> --- a/drivers/irqchip/irq-loongson-pch-pic.c
>> +++ b/drivers/irqchip/irq-loongson-pch-pic.c
>> @@ -177,13 +177,15 @@ static int pch_pic_domain_translate(struct irq_domain *d,
>>   	if (fwspec->param_count < 1)
>>   		return -EINVAL;
>>   
>> -	if (of_node) {
>> +	if (of_node)
>>   		*hwirq = fwspec->param[0] + priv->ht_vec_base;
>> -		*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
>> -	} else {
>> +	else
>>   		*hwirq = fwspec->param[0] - priv->gsi_base;
>> +
>> +	if (fwspec->param_count > 1)
>> +		*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
>> +	else
>>   		*type = IRQ_TYPE_NONE;
> 
> Isn't that a change in behaviour if of_node is non-NULL and
> param_count==1?
> 

It seems that current code here has bug that if fwspec->param_count==1 
and of_node is non-null, fwspec->param[1] will be accessed, which is 
introduced from previous patch(irqchip/loongson-pch-pic: Add ACPI init 
support). Before the patch, for non-null of_node, translate callback(use 
irq_domain_translate_twocell) will return -EINVAL if fwspec->param_count 
< 2.

For ACPI path, fwspec->param_count can be 1 or 2.

So in this patch, I'll fix the bug and change the code as following:

         if (fwspec->param_count < 1)
                 return -EINVAL;

         if (of_node) {
                 if (fwspec->param_count < 2)
                         return -EINVAL;

                 *hwirq = fwspec->param[0] + priv->ht_vec_base;
                 *type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
         } else {
                 *hwirq = fwspec->param[0] - priv->gsi_base;

                 if (fwspec->param_count > 1)
                         *type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
                 else
                         *type = IRQ_TYPE_NONE;
         }


>> -	}
>>   
>>   	return 0;
>>   }
> 
> This irqchip change should probably be a separate patch.
> 

As a separate patch, the input trigger type of pci devices will be low 
level because of lacking of workaround to acpi_pci_irq_enable, which 
will cause kernel hang, unless the patch of workaround to 
acpi_pci_irq_enable is in front of this separated patch.


> 	M.
>