Re: [PATCH V3 2/3] Revert "ACPI,PCI,IRQ: remove SCI penalize function"

[Bjorn Helgaas <helgaas@kernel.org>]

On Sat, Oct 15, 2016 at 12:31:06AM -0400, Sinan Kaya wrote:
> The SCI function was removed in two steps (first refactor and then remove).
> This patch does the revert in one step.
> 
> The commit 103544d86976 ("ACPI,PCI,IRQ: reduce resource requirements")
> refactored the original code so that SCI penalty is calculated dynamically
> by the time get_penalty function is called. This patch does a partial
> revert for the SCI functionality only.
> 
> The commit 9e5ed6d1fb87 ("ACPI,PCI,IRQ: remove SCI penalize function") is
> for the removal of the function. SCI penalty API was replaced by the
> runtime penalty calculation based on the value of
> acpi_gbl_FADT.sci_interrupt.
> 
> The IRQ type does not get updated at the right time for some platforms and
> results in incorrect penalty assignment for PCI IRQs as
> irq_get_trigger_type returns the wrong type.
> 
> The register_gsi function delivers the IRQ found in the ACPI table to
> the interrupt controller driver.  Penalties are calculated before a
> link object is enabled to find out which interrupt has the least number
> of users. By the time penalties are calculated, the IRQ is not registered
> yet and the API returns the wrong type.

I think you should squash patches 2 & 3 and not bother with trying to
make this a revert followed by a fix.  Squashing them makes the git
history much easier to follow, plus you don't have to deal with the
headache of ensuring the intermediate state is correct and bisectable.

> Tested-by: Jonathan Liu <net147@gmail.com>
> Tested-by: Ondrej Zary <linux@rainbow-software.org>
> Link: https://lkml.org/lkml/2016/10/4/283
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> Acked-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  arch/x86/kernel/acpi/boot.c |  1 +
>  drivers/acpi/pci_link.c     | 32 +++++++++++++-------------------
>  include/linux/acpi.h        |  1 +
>  3 files changed, 15 insertions(+), 19 deletions(-)
> 
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 90d84c3..0ffd26e 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -453,6 +453,7 @@ static void __init acpi_sci_ioapic_setup(u8 bus_irq, u16 polarity, u16 trigger,
>  		polarity = acpi_sci_flags & ACPI_MADT_POLARITY_MASK;
>  
>  	mp_override_legacy_irq(bus_irq, polarity, trigger, gsi);
> +	acpi_penalize_sci_irq(bus_irq, trigger, polarity);
>  
>  	/*
>  	 * stash over-ride to indicate we've been here
> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
> index a212709..1934e2a 100644
> --- a/drivers/acpi/pci_link.c
> +++ b/drivers/acpi/pci_link.c
> @@ -494,27 +494,10 @@ static int acpi_irq_pci_sharing_penalty(int irq)
>  
>  static int acpi_irq_get_penalty(int irq)
>  {
> -	int penalty = 0;
> -
> -	/*
> -	* Penalize IRQ used by ACPI SCI. If ACPI SCI pin attributes conflict
> -	* with PCI IRQ attributes, mark ACPI SCI as ISA_ALWAYS so it won't be
> -	* use for PCI IRQs.
> -	*/
> -	if (irq == acpi_gbl_FADT.sci_interrupt) {
> -		u32 type = irq_get_trigger_type(irq) & IRQ_TYPE_SENSE_MASK;
> -
> -		if (type != IRQ_TYPE_LEVEL_LOW)
> -			penalty += PIRQ_PENALTY_ISA_ALWAYS;
> -		else
> -			penalty += PIRQ_PENALTY_PCI_USING;
> -	}
> -
>  	if (irq < ACPI_MAX_ISA_IRQS)
> -		return penalty + acpi_isa_irq_penalty[irq];
> +		return acpi_isa_irq_penalty[irq];
>  
> -	penalty += acpi_irq_pci_sharing_penalty(irq);
> -	return penalty;
> +	return acpi_irq_pci_sharing_penalty(irq);
>  }
>  
>  int __init acpi_irq_penalty_init(void)
> @@ -885,6 +868,17 @@ bool acpi_isa_irq_available(int irq)
>  		    acpi_irq_get_penalty(irq) < PIRQ_PENALTY_ISA_ALWAYS);
>  }
>  
> +void acpi_penalize_sci_irq(int irq, int trigger, int polarity)
> +{
> +	if (irq >= 0 && irq < ARRAY_SIZE(acpi_isa_irq_penalty)) {
> +		if (trigger != ACPI_MADT_TRIGGER_LEVEL ||
> +		    polarity != ACPI_MADT_POLARITY_ACTIVE_LOW)
> +			acpi_isa_irq_penalty[irq] += PIRQ_PENALTY_ISA_ALWAYS;
> +		else
> +			acpi_isa_irq_penalty[irq] += PIRQ_PENALTY_PCI_USING;
> +	}
> +}
> +
>  /*
>   * Over-ride default table to reserve additional IRQs for use by ISA
>   * e.g. acpi_irq_isa=5
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index c5eaf2f..67d1d3e 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -318,6 +318,7 @@ struct pci_dev;
>  int acpi_pci_irq_enable (struct pci_dev *dev);
>  void acpi_penalize_isa_irq(int irq, int active);
>  bool acpi_isa_irq_available(int irq);
> +void acpi_penalize_sci_irq(int irq, int trigger, int polarity);
>  void acpi_pci_irq_disable (struct pci_dev *dev);
>  
>  extern int ec_read(u8 addr, u8 *val);
> -- 
> 1.9.1
> 
> 
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