Re: [PATCH V3 1/3] ACPI, PCI IRQ: add PCI_USING penalty for ISA interrupts

Sinan Kaya
2016-10-24T04:16:04Z

On 10/22/2016 7:58 PM, Bjorn Helgaas wrote:
> On Sat, Oct 15, 2016 at 12:31:05AM -0400, Sinan Kaya wrote:
>> The change introduced in commit 103544d86976 ("ACPI,PCI,IRQ: reduce
>> resource requirements") removed PCI_USING penalty from
>> acpi_pci_link_allocate function as there is no longer a fixed size penalty
>> array for both PCI interrupts greater than 16.
>>
>> The array size has been reduced to 16 and array name got prefixed as ISA
>> since it only is accountable for the ISA interrupts.
>>
>> The original change in commit 103544d86976 ("ACPI,PCI,IRQ: reduce
>> resource requirements") removed penalty assignment in the code for PCI
>> thinking that we will add the penalty later in acpi_irq_pci_sharing_penalty
>> function.
>>
>> However, this function only gets called if the IRQ number is greater than
>> 16 and acpi_irq_get_penalty function gets called before ACPI start in
>> acpi_isa_irq_available and acpi_penalize_isa_irq functions. We can't rely
>> on iterating the link list.
>>
>> We need to add the PCI_USING penalty for ISA interrupts too if the link is
>> in use and matches our ISA IRQ number.
>
> I think the history about the array size is more than is necessary for this
> changelog. I think the useful part is something like this:
>
> ACPI: pci_link: Include PIRQ_PENALTY_PCI_USING for ISA IRQs
>
> 103544d86976 ("ACPI,PCI,IRQ: reduce resource requirements") replaced
> the addition of PIRQ_PENALTY_PCI_USING in acpi_pci_link_allocate()
> with an addition in acpi_irq_pci_sharing_penalty(), but f7eca374f000
> ("ACPI,PCI,IRQ: separate ISA penalty calculation") removed the use
> of acpi_irq_pci_sharing_penalty() for ISA IRQs.
>
> Therefore, PIRQ_PENALTY_PCI_USING is missing from ISA IRQs used by
> interrupt links. Include that penalty by adding it in the
> acpi_pci_link_allocate() path.
>
> Fixes: f7eca374f000 ("ACPI,PCI,IRQ: separate ISA penalty calculation")
>
>> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>

OK. Updated as suggested.

>
>> ---
>> drivers/acpi/pci_link.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
>> index c983bf7..a212709 100644
>> --- a/drivers/acpi/pci_link.c
>> +++ b/drivers/acpi/pci_link.c
>> @@ -619,6 +619,10 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
>> acpi_device_bid(link->device));
>> return -ENODEV;
>> } else {
>> + if (link->irq.active < ACPI_MAX_ISA_IRQS)
>> + acpi_isa_irq_penalty[link->irq.active] +=
>> + PIRQ_PENALTY_PCI_USING;
>> +
>> printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n",
>> acpi_device_name(link->device),
>> acpi_device_bid(link->device), link->irq.active);
>> --
>> 1.9.1
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.