[PATCH V4 2/3] Revert "ACPI,PCI,IRQ: remove SCI penalize function"

[Sinan Kaya]

The SCI penalize function was removed in two steps (first refactor
and then remove) and these changes are reverted here in one go.

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. That change is partially
reverted here, specifically for the SCI IRQ alone.

The SCI penalize function was finally dropped by commit 9e5ed6d1fb87
("ACPI,PCI,IRQ: remove SCI penalize function") that replaced the old SCI
penalty API with penalty calculation carried out dynamically and based
on the acpi_gbl_FADT.sci_interrupt value.

However, that new algorithm relies on the accurate setting of IRQ
types and that doesn't happen early enough on some platforms which
leads to incorrect penalty assignments for PCI IRQs.  In those cases,
irq_get_trigger_type() returns incorrect values for the IRQs in
question, because they have not been registered yet by the time the
penalties are calculated.

To fix this problem, we only need to fix the penalty for the SCI interrupt.
It seems better to add a single "sci_penalty" variable, set it to
PIRQ_PENALTY_PCI_USING if it's level/low or PIRQ_PENALTY_ISA_ALWAYS
otherwise, and add "sci_penalty" in when appropriate.  That should fix it
for *any* SCI IRQ, not just those less than 256, and we don't have to add
these extra penalty table entries that are all unused (except possibly for
one entry if we have an SCI in the 16-255 range).

For this reason, revert commit 9e5ed6d1fb87 ("ACPI,PCI,IRQ: remove SCI
penalize function") completely to restore the correct behavior.

Link: https://lkml.org/lkml/2016/10/4/283
Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>
Fixes: commit 103544d86976 ("ACPI,PCI,IRQ: reduce resource requirements")
Fixes: commit 9e5ed6d1fb87 ("ACPI,PCI,IRQ: remove SCI penalize function")
---
 arch/x86/kernel/acpi/boot.c |  1 +
 drivers/acpi/pci_link.c     | 30 +++++++++++++++---------------
 include/linux/acpi.h        |  1 +
 3 files changed, 17 insertions(+), 15 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 4f37938..294b190 100644
--- a/drivers/acpi/pci_link.c
+++ b/drivers/acpi/pci_link.c
@@ -87,6 +87,7 @@ struct acpi_pci_link {
 
 static LIST_HEAD(acpi_link_list);
 static DEFINE_MUTEX(acpi_link_lock);
+static int sci_irq = -1, sci_penalty;
 
 /* --------------------------------------------------------------------------
                             PCI Link Device Management
@@ -496,25 +497,13 @@ 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 == sci_irq)
+		penalty += sci_penalty;
 
 	if (irq < ACPI_MAX_ISA_IRQS)
 		return penalty + acpi_isa_irq_penalty[irq];
 
-	penalty += acpi_irq_pci_sharing_penalty(irq);
-	return penalty;
+	return penalty + acpi_irq_pci_sharing_penalty(irq);
 }
 
 int __init acpi_irq_penalty_init(void)
@@ -881,6 +870,17 @@ 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)
+{
+	sci_irq = irq;
+
+	if (trigger == ACPI_MADT_TRIGGER_LEVEL &&
+	    polarity == ACPI_MADT_POLARITY_ACTIVE_LOW)
+		sci_penalty = PIRQ_PENALTY_PCI_USING;
+	else
+		sci_penalty = PIRQ_PENALTY_ISA_ALWAYS;
+}
+
 /*
  * 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