Re: [PATCH V4 3/3] Revert "ACPI, PCI, IRQ: separate ISA penalty calculation"

Bjorn Helgaas
2016-10-21T02:31:18Z

On Wed, Oct 19, 2016 at 06:21:04PM -0400, Sinan Kaya wrote:
> This reverts commit f7eca374f000 ("ACPI,PCI,IRQ: separate ISA penalty
> calculation") and commit 487cf917ed0d ("revert "ACPI, PCI, IRQ: remove
> redundant code in acpi_irq_penalty_init()"").
>
> Now that we understand the real issue (SCI and ISA penalty getting
> calculated before ACPI start), there is no need for special handling
> for ISA interrupts.
>
> Let's try to simplify the code one more time to share code.

I'm sort of OK with this, but it's not exactly a revert of the above
(the commits you mention don't check "link->irq.initialized == 1".

Previously acpi_irq_penalty_init() looked at _PRS info ("possible"
IRQs), but now we won't. Maybe that's good; I dunno. But it should
be mentioned.

And I don't think it fixes a user-visible problem, so it doesn't need
to be applied immediately. I'm not sure this is worth doing by
itself; maybe it should wait until we can do more cleanup and think
about all these issues together?

> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
> arch/x86/pci/acpi.c | 1 -
> drivers/acpi/pci_link.c | 44 +++++---------------------------------------
> include/acpi/acpi_drivers.h | 1 -
> 3 files changed, 5 insertions(+), 41 deletions(-)
>
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index 3cd6983..b2a4e2a 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -396,7 +396,6 @@ int __init pci_acpi_init(void)
> return -ENODEV;
>
> printk(KERN_INFO "PCI: Using ACPI for IRQ routing\n");
> - acpi_irq_penalty_init();
> pcibios_enable_irq = acpi_pci_irq_enable;
> pcibios_disable_irq = acpi_pci_irq_disable;
> x86_init.pci.init_irq = x86_init_noop;
> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
> index 294b190..dd14d78 100644
> --- a/drivers/acpi/pci_link.c
> +++ b/drivers/acpi/pci_link.c
> @@ -478,7 +478,8 @@ static int acpi_irq_pci_sharing_penalty(int irq)
> * If a link is active, penalize its IRQ heavily
> * so we try to choose a different IRQ.
> */
> - if (link->irq.active && link->irq.active == irq)
> + if ((link->irq.active && link->irq.active == irq) &&
> + (link->irq.initialized == 1))
> penalty += PIRQ_PENALTY_PCI_USING;
>
> /*
> @@ -501,45 +502,10 @@ static int acpi_irq_get_penalty(int irq)
> penalty += sci_penalty;
>
> if (irq < ACPI_MAX_ISA_IRQS)
> - return penalty + acpi_isa_irq_penalty[irq];
> + penalty += acpi_isa_irq_penalty[irq];
>
> - return penalty + acpi_irq_pci_sharing_penalty(irq);
> -}
> -
> -int __init acpi_irq_penalty_init(void)
> -{
> - struct acpi_pci_link *link;
> - int i;
> -
> - /*
> - * Update penalties to facilitate IRQ balancing.
> - */
> - list_for_each_entry(link, &acpi_link_list, list) {
> -
> - /*
> - * reflect the possible and active irqs in the penalty table --
> - * useful for breaking ties.
> - */
> - if (link->irq.possible_count) {
> - int penalty =
> - PIRQ_PENALTY_PCI_POSSIBLE /
> - link->irq.possible_count;
> -
> - for (i = 0; i < link->irq.possible_count; i++) {
> - if (link->irq.possible[i] < ACPI_MAX_ISA_IRQS)
> - acpi_isa_irq_penalty[link->irq.
> - possible[i]] +=
> - penalty;
> - }
> -
> - } else if (link->irq.active &&
> - (link->irq.active < ACPI_MAX_ISA_IRQS)) {
> - acpi_isa_irq_penalty[link->irq.active] +=
> - PIRQ_PENALTY_PCI_POSSIBLE;
> - }
> - }
> -
> - return 0;
> + penalty += acpi_irq_pci_sharing_penalty(irq);
> + return penalty;
> }
>
> static int acpi_irq_balance = -1; /* 0: static, 1: balance */
> diff --git a/include/acpi/acpi_drivers.h b/include/acpi/acpi_drivers.h
> index 29c6912..797ae2e 100644
> --- a/include/acpi/acpi_drivers.h
> +++ b/include/acpi/acpi_drivers.h
> @@ -78,7 +78,6 @@
>
> /* ACPI PCI Interrupt Link (pci_link.c) */
>
> -int acpi_irq_penalty_init(void);
> int acpi_pci_link_allocate_irq(acpi_handle handle, int index, int *triggering,
> int *polarity, char **name);
> int acpi_pci_link_free_irq(acpi_handle handle);
> --
> 1.9.1
>
>
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