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

> ---
> 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

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