[PATCH V2 0/3] simplify ACPI PCI IRQ code

[PATCH V2 0/3] simplify ACPI PCI IRQ code

[Sinan Kaya]

differences from V1: https://patchwork.ozlabs.org/patch/599869/

Implement acpi_link_trigger and acpi_pci_compatible_trigger functions to
validate that all requesters agree on the IRQ polarity and trigger before
claiming for PCI and SCI interrupts.


Sinan Kaya (3):
  acpi,pci,irq: reduce resource requirements
  acpi,pci,irq: remove redundant code in acpi_irq_penalty_init
  acpi,pci,irq: remove SCI penalize function

 arch/x86/kernel/acpi/boot.c |   1 -
 arch/x86/pci/acpi.c         |   1 -
 drivers/acpi/pci_link.c     | 185 +++++++++++++++++++++++++++++---------------
 include/acpi/acpi_drivers.h |   1 -
 include/linux/acpi.h        |   1 -
 5 files changed, 122 insertions(+), 67 deletions(-)

-- 
1.8.2.1

[PATCH V2 1/3] acpi,pci,irq: reduce resource requirements

[Sinan Kaya]

Code has been redesigned to calculate penalty requirements on the fly. This
significantly simplifies the implementation and removes some of the init
calls from x86 architecture. Command line penalty assignment has been
limited to ISA interrupts only.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/acpi/pci_link.c | 176 ++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 140 insertions(+), 36 deletions(-)

diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
index ededa90..25695ea 100644
--- a/drivers/acpi/pci_link.c
+++ b/drivers/acpi/pci_link.c
@@ -437,17 +437,15 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
  * enabled system.
  */
 
-#define ACPI_MAX_IRQS		256
 #define ACPI_MAX_ISA_IRQ	16
 
-#define PIRQ_PENALTY_PCI_AVAILABLE	(0)
 #define PIRQ_PENALTY_PCI_POSSIBLE	(16*16)
 #define PIRQ_PENALTY_PCI_USING		(16*16*16)
 #define PIRQ_PENALTY_ISA_TYPICAL	(16*16*16*16)
 #define PIRQ_PENALTY_ISA_USED		(16*16*16*16*16)
 #define PIRQ_PENALTY_ISA_ALWAYS		(16*16*16*16*16*16)
 
-static int acpi_irq_penalty[ACPI_MAX_IRQS] = {
+static int acpi_isa_irq_penalty[ACPI_MAX_ISA_IRQ] = {
 	PIRQ_PENALTY_ISA_ALWAYS,	/* IRQ0 timer */
 	PIRQ_PENALTY_ISA_ALWAYS,	/* IRQ1 keyboard */
 	PIRQ_PENALTY_ISA_ALWAYS,	/* IRQ2 cascade */
@@ -457,9 +455,9 @@ static int acpi_irq_penalty[ACPI_MAX_IRQS] = {
 	PIRQ_PENALTY_ISA_TYPICAL,	/* IRQ6 */
 	PIRQ_PENALTY_ISA_TYPICAL,	/* IRQ7 parallel, spurious */
 	PIRQ_PENALTY_ISA_TYPICAL,	/* IRQ8 rtc, sometimes */
-	PIRQ_PENALTY_PCI_AVAILABLE,	/* IRQ9  PCI, often acpi */
-	PIRQ_PENALTY_PCI_AVAILABLE,	/* IRQ10 PCI */
-	PIRQ_PENALTY_PCI_AVAILABLE,	/* IRQ11 PCI */
+	0,				/* IRQ9  PCI, often acpi */
+	0,				/* IRQ10 PCI */
+	0,				/* IRQ11 PCI */
 	PIRQ_PENALTY_ISA_USED,		/* IRQ12 mouse */
 	PIRQ_PENALTY_ISA_USED,		/* IRQ13 fpe, sometimes */
 	PIRQ_PENALTY_ISA_USED,		/* IRQ14 ide0 */
@@ -467,6 +465,121 @@ static int acpi_irq_penalty[ACPI_MAX_IRQS] = {
 	/* >IRQ15 */
 };
 
+static int acpi_link_trigger(int irq, u8 *polarity, u8 *triggering)
+{
+	struct acpi_pci_link *link;
+	bool found = false;
+
+	*polarity = ~0;
+	*triggering = ~0;
+
+	list_for_each_entry(link, &acpi_link_list, list) {
+		int i;
+
+		if (link->irq.active && link->irq.active == irq) {
+			if (*polarity == ~0)
+				*polarity = link->irq.polarity;
+
+			if (*triggering == ~0)
+				*triggering = link->irq.triggering;
+
+			if (*polarity != link->irq.polarity)
+				return -EINVAL;
+
+			if (*triggering != link->irq.triggering)
+				return -EINVAL;
+
+			found = true;
+		}
+
+		for (i = 0; i < link->irq.possible_count; i++)
+			if (link->irq.possible[i] == irq) {
+				if (*polarity == ~0)
+					*polarity = link->irq.polarity;
+
+				if (*triggering == ~0)
+					*triggering = link->irq.triggering;
+
+				if (*polarity != link->irq.polarity)
+					return -EINVAL;
+
+				if (*triggering != link->irq.triggering)
+					return -EINVAL;
+
+				found = true;
+			}
+	}
+
+	return found ? 0 : -EINVAL;
+}
+
+static int acpi_pci_compatible_trigger(int irq)
+{
+	u8 polarity;
+	u8 triggering;
+
+	return acpi_link_trigger(irq, &polarity, &triggering);
+}
+
+static int acpi_irq_pci_sharing_penalty(int irq)
+{
+	struct acpi_pci_link *link;
+	int penalty = 0;
+
+	if (acpi_pci_compatible_trigger(irq))
+		return ~0;
+
+	list_for_each_entry(link, &acpi_link_list, list) {
+		/*
+		 * 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)
+			penalty += PIRQ_PENALTY_PCI_USING;
+		else {
+			int i;
+
+			/*
+			 * If a link is inactive, penalize the IRQs it
+			 * might use, but not as severely.
+			 */
+			for (i = 0; i < link->irq.possible_count; i++)
+				if (link->irq.possible[i] == irq)
+					penalty += PIRQ_PENALTY_PCI_POSSIBLE /
+						link->irq.possible_count;
+		}
+	}
+
+	return penalty;
+}
+
+static int acpi_irq_get_penalty(int irq)
+{
+	int penalty = 0, rc;
+
+	if (irq < ACPI_MAX_ISA_IRQ)
+		penalty += acpi_isa_irq_penalty[irq];
+
+	if (irq == acpi_gbl_FADT.sci_interrupt) {
+		u8 sci_polarity;
+		u8 sci_trigger;
+
+		rc = acpi_link_trigger(irq, &sci_polarity, &sci_trigger);
+		if (!rc) {
+			if (sci_trigger != ACPI_LEVEL_SENSITIVE ||
+			    sci_polarity != ACPI_ACTIVE_LOW)
+				penalty += PIRQ_PENALTY_ISA_ALWAYS;
+			else
+				penalty += PIRQ_PENALTY_PCI_USING;
+		} else {
+			return ~0;
+		}
+	}
+
+	penalty += acpi_irq_pci_sharing_penalty(irq);
+	return penalty;
+}
+
 int __init acpi_irq_penalty_init(void)
 {
 	struct acpi_pci_link *link;
@@ -488,13 +601,14 @@ int __init acpi_irq_penalty_init(void)
 
 			for (i = 0; i < link->irq.possible_count; i++) {
 				if (link->irq.possible[i] < ACPI_MAX_ISA_IRQ)
-					acpi_irq_penalty[link->irq.
-							 possible[i]] +=
+					acpi_isa_irq_penalty[link->irq.
+							     possible[i]] +=
 					    penalty;
 			}
 
-		} else if (link->irq.active) {
-			acpi_irq_penalty[link->irq.active] +=
+		} else if (link->irq.active &&
+			   (link->irq.active < ACPI_MAX_ISA_IRQ)) {
+			acpi_isa_irq_penalty[link->irq.active] +=
 			    PIRQ_PENALTY_PCI_POSSIBLE;
 		}
 	}
@@ -547,12 +661,12 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
 		 * the use of IRQs 9, 10, 11, and >15.
 		 */
 		for (i = (link->irq.possible_count - 1); i >= 0; i--) {
-			if (acpi_irq_penalty[irq] >
-			    acpi_irq_penalty[link->irq.possible[i]])
+			if (acpi_irq_get_penalty(irq) >
+			    acpi_irq_get_penalty(link->irq.possible[i]))
 				irq = link->irq.possible[i];
 		}
 	}
-	if (acpi_irq_penalty[irq] >= PIRQ_PENALTY_ISA_ALWAYS) {
+	if (acpi_irq_get_penalty(irq) >= PIRQ_PENALTY_ISA_ALWAYS) {
 		printk(KERN_ERR PREFIX "No IRQ available for %s [%s]. "
 			    "Try pci=noacpi or acpi=off\n",
 			    acpi_device_name(link->device),
@@ -568,7 +682,6 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
 			    acpi_device_bid(link->device));
 		return -ENODEV;
 	} else {
-		acpi_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);
@@ -778,7 +891,7 @@ static void acpi_pci_link_remove(struct acpi_device *device)
 }
 
 /*
- * modify acpi_irq_penalty[] from cmdline
+ * modify acpi_isa_irq_penalty[] from cmdline
  */
 static int __init acpi_irq_penalty_update(char *str, int used)
 {
@@ -787,23 +900,24 @@ static int __init acpi_irq_penalty_update(char *str, int used)
 	for (i = 0; i < 16; i++) {
 		int retval;
 		int irq;
+		int new_penalty;
 
 		retval = get_option(&str, &irq);
 
 		if (!retval)
 			break;	/* no number found */
 
-		if (irq < 0)
-			continue;
-
-		if (irq >= ARRAY_SIZE(acpi_irq_penalty))
+		/* see if this is a ISA IRQ */
+		if ((irq < 0) || (irq >= ACPI_MAX_ISA_IRQ))
 			continue;
 
 		if (used)
-			acpi_irq_penalty[irq] += PIRQ_PENALTY_ISA_USED;
+			new_penalty = acpi_irq_get_penalty(irq) +
+					PIRQ_PENALTY_ISA_USED;
 		else
-			acpi_irq_penalty[irq] = PIRQ_PENALTY_PCI_AVAILABLE;
+			new_penalty = 0;
 
+		acpi_isa_irq_penalty[irq] = new_penalty;
 		if (retval != 2)	/* no next number */
 			break;
 	}
@@ -819,18 +933,15 @@ static int __init acpi_irq_penalty_update(char *str, int used)
  */
 void acpi_penalize_isa_irq(int irq, int active)
 {
-	if (irq >= 0 && irq < ARRAY_SIZE(acpi_irq_penalty)) {
-		if (active)
-			acpi_irq_penalty[irq] += PIRQ_PENALTY_ISA_USED;
-		else
-			acpi_irq_penalty[irq] += PIRQ_PENALTY_PCI_USING;
-	}
+	if ((irq >= 0) && (irq < ARRAY_SIZE(acpi_isa_irq_penalty)))
+		acpi_isa_irq_penalty[irq] = active ?
+			PIRQ_PENALTY_ISA_USED : PIRQ_PENALTY_PCI_USING;
 }
 
 bool acpi_isa_irq_available(int irq)
 {
-	return irq >= 0 && (irq >= ARRAY_SIZE(acpi_irq_penalty) ||
-			    acpi_irq_penalty[irq] < PIRQ_PENALTY_ISA_ALWAYS);
+	return irq >= 0 && (irq >= ARRAY_SIZE(acpi_isa_irq_penalty) ||
+			 acpi_isa_irq_penalty[irq] < PIRQ_PENALTY_ISA_ALWAYS);
 }
 
 /*
@@ -840,13 +951,6 @@ bool acpi_isa_irq_available(int irq)
  */
 void acpi_penalize_sci_irq(int irq, int trigger, int polarity)
 {
-	if (irq >= 0 && irq < ARRAY_SIZE(acpi_irq_penalty)) {
-		if (trigger != ACPI_MADT_TRIGGER_LEVEL ||
-		    polarity != ACPI_MADT_POLARITY_ACTIVE_LOW)
-			acpi_irq_penalty[irq] += PIRQ_PENALTY_ISA_ALWAYS;
-		else
-			acpi_irq_penalty[irq] += PIRQ_PENALTY_PCI_USING;
-	}
 }
 
 /*
-- 
1.8.2.1

[PATCH V2 2/3] acpi,pci,irq: remove redundant code in acpi_irq_penalty_init

[Sinan Kaya]

acpi_irq_get_penalty is now calculating the penalty on the fly now.
No need to maintain global list of penalties or calculate them
at the init time. Removing duplicate code in acpi_irq_penalty_init.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 arch/x86/pci/acpi.c         |  1 -
 drivers/acpi/pci_link.c     | 36 ------------------------------------
 include/acpi/acpi_drivers.h |  1 -
 3 files changed, 38 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 25695ea..63dae95 100644
--- a/drivers/acpi/pci_link.c
+++ b/drivers/acpi/pci_link.c
@@ -580,42 +580,6 @@ static int acpi_irq_get_penalty(int irq)
 	return penalty;
 }
 
-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_IRQ)
-					acpi_isa_irq_penalty[link->irq.
-							     possible[i]] +=
-					    penalty;
-			}
-
-		} else if (link->irq.active &&
-			   (link->irq.active < ACPI_MAX_ISA_IRQ)) {
-			acpi_isa_irq_penalty[link->irq.active] +=
-			    PIRQ_PENALTY_PCI_POSSIBLE;
-		}
-	}
-
-	return 0;
-}
-
 static int acpi_irq_balance = -1;	/* 0: static, 1: balance */
 
 static int acpi_pci_link_allocate(struct acpi_pci_link *link)
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);
-- 
1.8.2.1

[PATCH V2 3/3] acpi,pci,irq: remove SCI penalize function

[Sinan Kaya]

Removing the SCI penalize function as the penalty is now calculated on the
fly.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 arch/x86/kernel/acpi/boot.c | 1 -
 drivers/acpi/pci_link.c     | 9 ---------
 include/linux/acpi.h        | 1 -
 3 files changed, 11 deletions(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index e759076..5e99f22 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -445,7 +445,6 @@ 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 63dae95..5b9a2d0 100644
--- a/drivers/acpi/pci_link.c
+++ b/drivers/acpi/pci_link.c
@@ -909,15 +909,6 @@ bool acpi_isa_irq_available(int irq)
 }
 
 /*
- * 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.
- */
-void acpi_penalize_sci_irq(int irq, int trigger, int polarity)
-{
-}
-
-/*
  * Over-ride default table to reserve additional IRQs for use by ISA
  * e.g. acpi_irq_isa=5
  * Useful for telling ACPI how not to interfere with your ISA sound card.
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 06ed7e5..0f41317 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -311,7 +311,6 @@ 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);
-- 
1.8.2.1

Re: [PATCH V2 1/3] acpi,pci,irq: reduce resource requirements

[Bjorn Helgaas]

Hi Sinan,

I was hoping we could *simplify* this, but I think it's just getting
even more complicated (it's a net addition of 100 lines), which is due
to feature creep that I'm afraid is my fault.

IIRC, the main thing you need is to get rid of some early memory
allocation.

I don't think all the trigger mode/level checking is worth it.  The
current code doesn't do it, and it's not fixing a problem for you.
It's conceivable that it could even make us trip over a new problem,
e.g., some broken BIOS that we currently tolerate.

I think you could make this a little easier to review if you split
things like the acpi_irq_penalty[] -> acpi_isa_irq_penalty[] rename
into their own patches.  Little patches like that are trivial to
review because a simple rename is pretty safe, and then the patches
that actually *do* interesting things are smaller and easier to
review, too.

On Fri, Apr 08, 2016 at 09:26:30PM -0400, Sinan Kaya wrote:
> Code has been redesigned to calculate penalty requirements on the fly. This
> significantly simplifies the implementation and removes some of the init
> calls from x86 architecture. Command line penalty assignment has been
> limited to ISA interrupts only.
> 
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
>  drivers/acpi/pci_link.c | 176 ++++++++++++++++++++++++++++++++++++++----------
>  1 file changed, 140 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
> index ededa90..25695ea 100644
> --- a/drivers/acpi/pci_link.c
> +++ b/drivers/acpi/pci_link.c
> @@ -437,17 +437,15 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
>   * enabled system.
>   */
>  
> -#define ACPI_MAX_IRQS		256
>  #define ACPI_MAX_ISA_IRQ	16

ACPI_MAX_ISA_IRQ is a bit of a misnomer.  The maximum ISA IRQ is 15,
not 16, so I think this should be named ACPI_MAX_ISA_IRQS.

> -#define PIRQ_PENALTY_PCI_AVAILABLE	(0)
>  #define PIRQ_PENALTY_PCI_POSSIBLE	(16*16)
>  #define PIRQ_PENALTY_PCI_USING		(16*16*16)
>  #define PIRQ_PENALTY_ISA_TYPICAL	(16*16*16*16)
>  #define PIRQ_PENALTY_ISA_USED		(16*16*16*16*16)
>  #define PIRQ_PENALTY_ISA_ALWAYS		(16*16*16*16*16*16)
>  
> -static int acpi_irq_penalty[ACPI_MAX_IRQS] = {
> +static int acpi_isa_irq_penalty[ACPI_MAX_ISA_IRQ] = {
>  	PIRQ_PENALTY_ISA_ALWAYS,	/* IRQ0 timer */
>  	PIRQ_PENALTY_ISA_ALWAYS,	/* IRQ1 keyboard */
>  	PIRQ_PENALTY_ISA_ALWAYS,	/* IRQ2 cascade */
> @@ -457,9 +455,9 @@ static int acpi_irq_penalty[ACPI_MAX_IRQS] = {
>  	PIRQ_PENALTY_ISA_TYPICAL,	/* IRQ6 */
>  	PIRQ_PENALTY_ISA_TYPICAL,	/* IRQ7 parallel, spurious */
>  	PIRQ_PENALTY_ISA_TYPICAL,	/* IRQ8 rtc, sometimes */
> -	PIRQ_PENALTY_PCI_AVAILABLE,	/* IRQ9  PCI, often acpi */
> -	PIRQ_PENALTY_PCI_AVAILABLE,	/* IRQ10 PCI */
> -	PIRQ_PENALTY_PCI_AVAILABLE,	/* IRQ11 PCI */
> +	0,				/* IRQ9  PCI, often acpi */
> +	0,				/* IRQ10 PCI */
> +	0,				/* IRQ11 PCI */
>  	PIRQ_PENALTY_ISA_USED,		/* IRQ12 mouse */
>  	PIRQ_PENALTY_ISA_USED,		/* IRQ13 fpe, sometimes */
>  	PIRQ_PENALTY_ISA_USED,		/* IRQ14 ide0 */
> @@ -467,6 +465,121 @@ static int acpi_irq_penalty[ACPI_MAX_IRQS] = {
>  	/* >IRQ15 */
>  };
>  
> +static int acpi_link_trigger(int irq, u8 *polarity, u8 *triggering)
> +{
> +	struct acpi_pci_link *link;
> +	bool found = false;
> +
> +	*polarity = ~0;
> +	*triggering = ~0;
> +
> +	list_for_each_entry(link, &acpi_link_list, list) {
> +		int i;
> +
> +		if (link->irq.active && link->irq.active == irq) {
> +			if (*polarity == ~0)
> +				*polarity = link->irq.polarity;
> +
> +			if (*triggering == ~0)
> +				*triggering = link->irq.triggering;
> +
> +			if (*polarity != link->irq.polarity)
> +				return -EINVAL;
> +
> +			if (*triggering != link->irq.triggering)
> +				return -EINVAL;
> +
> +			found = true;
> +		}
> +
> +		for (i = 0; i < link->irq.possible_count; i++)
> +			if (link->irq.possible[i] == irq) {
> +				if (*polarity == ~0)
> +					*polarity = link->irq.polarity;
> +
> +				if (*triggering == ~0)
> +					*triggering = link->irq.triggering;
> +
> +				if (*polarity != link->irq.polarity)
> +					return -EINVAL;
> +
> +				if (*triggering != link->irq.triggering)
> +					return -EINVAL;
> +
> +				found = true;
> +			}
> +	}
> +
> +	return found ? 0 : -EINVAL;
> +}
> +
> +static int acpi_pci_compatible_trigger(int irq)
> +{
> +	u8 polarity;
> +	u8 triggering;
> +
> +	return acpi_link_trigger(irq, &polarity, &triggering);
> +}
> +
> +static int acpi_irq_pci_sharing_penalty(int irq)
> +{
> +	struct acpi_pci_link *link;
> +	int penalty = 0;
> +
> +	if (acpi_pci_compatible_trigger(irq))
> +		return ~0;

This is the part (and all the acpi_link_trigger() code) that I think
is new functionality we didn't have before, and maybe not worth doing.
If we *do* want it, I think it should be added in a separate patch.

> +
> +	list_for_each_entry(link, &acpi_link_list, list) {
> +		/*
> +		 * 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)
> +			penalty += PIRQ_PENALTY_PCI_USING;
> +		else {
> +			int i;
> +
> +			/*
> +			 * If a link is inactive, penalize the IRQs it
> +			 * might use, but not as severely.
> +			 */
> +			for (i = 0; i < link->irq.possible_count; i++)
> +				if (link->irq.possible[i] == irq)
> +					penalty += PIRQ_PENALTY_PCI_POSSIBLE /
> +						link->irq.possible_count;
> +		}
> +	}
> +
> +	return penalty;
> +}
> +
> +static int acpi_irq_get_penalty(int irq)
> +{
> +	int penalty = 0, rc;
> +
> +	if (irq < ACPI_MAX_ISA_IRQ)
> +		penalty += acpi_isa_irq_penalty[irq];
> +
> +	if (irq == acpi_gbl_FADT.sci_interrupt) {
> +		u8 sci_polarity;
> +		u8 sci_trigger;
> +
> +		rc = acpi_link_trigger(irq, &sci_polarity, &sci_trigger);
> +		if (!rc) {
> +			if (sci_trigger != ACPI_LEVEL_SENSITIVE ||
> +			    sci_polarity != ACPI_ACTIVE_LOW)
> +				penalty += PIRQ_PENALTY_ISA_ALWAYS;
> +			else
> +				penalty += PIRQ_PENALTY_PCI_USING;
> +		} else {
> +			return ~0;

This function (acpi_irq_get_penalty()) returns a signed int,
and I don't think ~0 is the largest possible signed int.

> +		}
> +	}
> +
> +	penalty += acpi_irq_pci_sharing_penalty(irq);
> +	return penalty;
> +}
> +
>  int __init acpi_irq_penalty_init(void)
>  {
>  	struct acpi_pci_link *link;
> @@ -488,13 +601,14 @@ int __init acpi_irq_penalty_init(void)
>  
>  			for (i = 0; i < link->irq.possible_count; i++) {
>  				if (link->irq.possible[i] < ACPI_MAX_ISA_IRQ)
> -					acpi_irq_penalty[link->irq.
> -							 possible[i]] +=
> +					acpi_isa_irq_penalty[link->irq.
> +							     possible[i]] +=
>  					    penalty;
>  			}
>  
> -		} else if (link->irq.active) {
> -			acpi_irq_penalty[link->irq.active] +=
> +		} else if (link->irq.active &&
> +			   (link->irq.active < ACPI_MAX_ISA_IRQ)) {
> +			acpi_isa_irq_penalty[link->irq.active] +=
>  			    PIRQ_PENALTY_PCI_POSSIBLE;
>  		}
>  	}
> @@ -547,12 +661,12 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
>  		 * the use of IRQs 9, 10, 11, and >15.
>  		 */
>  		for (i = (link->irq.possible_count - 1); i >= 0; i--) {
> -			if (acpi_irq_penalty[irq] >
> -			    acpi_irq_penalty[link->irq.possible[i]])
> +			if (acpi_irq_get_penalty(irq) >
> +			    acpi_irq_get_penalty(link->irq.possible[i]))
>  				irq = link->irq.possible[i];
>  		}
>  	}
> -	if (acpi_irq_penalty[irq] >= PIRQ_PENALTY_ISA_ALWAYS) {
> +	if (acpi_irq_get_penalty(irq) >= PIRQ_PENALTY_ISA_ALWAYS) {
>  		printk(KERN_ERR PREFIX "No IRQ available for %s [%s]. "
>  			    "Try pci=noacpi or acpi=off\n",
>  			    acpi_device_name(link->device),
> @@ -568,7 +682,6 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
>  			    acpi_device_bid(link->device));
>  		return -ENODEV;
>  	} else {
> -		acpi_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);
> @@ -778,7 +891,7 @@ static void acpi_pci_link_remove(struct acpi_device *device)
>  }
>  
>  /*
> - * modify acpi_irq_penalty[] from cmdline
> + * modify acpi_isa_irq_penalty[] from cmdline
>   */
>  static int __init acpi_irq_penalty_update(char *str, int used)
>  {
> @@ -787,23 +900,24 @@ static int __init acpi_irq_penalty_update(char *str, int used)
>  	for (i = 0; i < 16; i++) {
>  		int retval;
>  		int irq;
> +		int new_penalty;
>  
>  		retval = get_option(&str, &irq);
>  
>  		if (!retval)
>  			break;	/* no number found */
>  
> -		if (irq < 0)
> -			continue;
> -
> -		if (irq >= ARRAY_SIZE(acpi_irq_penalty))
> +		/* see if this is a ISA IRQ */
> +		if ((irq < 0) || (irq >= ACPI_MAX_ISA_IRQ))
>  			continue;
>  
>  		if (used)
> -			acpi_irq_penalty[irq] += PIRQ_PENALTY_ISA_USED;
> +			new_penalty = acpi_irq_get_penalty(irq) +
> +					PIRQ_PENALTY_ISA_USED;
>  		else
> -			acpi_irq_penalty[irq] = PIRQ_PENALTY_PCI_AVAILABLE;
> +			new_penalty = 0;
>  
> +		acpi_isa_irq_penalty[irq] = new_penalty;
>  		if (retval != 2)	/* no next number */
>  			break;
>  	}
> @@ -819,18 +933,15 @@ static int __init acpi_irq_penalty_update(char *str, int used)
>   */
>  void acpi_penalize_isa_irq(int irq, int active)
>  {
> -	if (irq >= 0 && irq < ARRAY_SIZE(acpi_irq_penalty)) {
> -		if (active)
> -			acpi_irq_penalty[irq] += PIRQ_PENALTY_ISA_USED;
> -		else
> -			acpi_irq_penalty[irq] += PIRQ_PENALTY_PCI_USING;
> -	}
> +	if ((irq >= 0) && (irq < ARRAY_SIZE(acpi_isa_irq_penalty)))
> +		acpi_isa_irq_penalty[irq] = active ?
> +			PIRQ_PENALTY_ISA_USED : PIRQ_PENALTY_PCI_USING;
>  }
>  
>  bool acpi_isa_irq_available(int irq)
>  {
> -	return irq >= 0 && (irq >= ARRAY_SIZE(acpi_irq_penalty) ||
> -			    acpi_irq_penalty[irq] < PIRQ_PENALTY_ISA_ALWAYS);
> +	return irq >= 0 && (irq >= ARRAY_SIZE(acpi_isa_irq_penalty) ||
> +			 acpi_isa_irq_penalty[irq] < PIRQ_PENALTY_ISA_ALWAYS);
>  }
>  
>  /*
> @@ -840,13 +951,6 @@ bool acpi_isa_irq_available(int irq)
>   */
>  void acpi_penalize_sci_irq(int irq, int trigger, int polarity)
>  {

There's a comment just above here that doesn't make any sense after
you remove the entire function body, so maybe you can just remove the
comment at the same time (or move it to the place this code moved to).

> -	if (irq >= 0 && irq < ARRAY_SIZE(acpi_irq_penalty)) {
> -		if (trigger != ACPI_MADT_TRIGGER_LEVEL ||
> -		    polarity != ACPI_MADT_POLARITY_ACTIVE_LOW)
> -			acpi_irq_penalty[irq] += PIRQ_PENALTY_ISA_ALWAYS;
> -		else
> -			acpi_irq_penalty[irq] += PIRQ_PENALTY_PCI_USING;
> -	}
>  }
>  
>  /*
> -- 
> 1.8.2.1
> 
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Re: [PATCH V2 1/3] acpi,pci,irq: reduce resource requirements

[Sinan Kaya]

On 4/12/2016 1:19 AM, Bjorn Helgaas wrote:
> Hi Sinan,
> 
> I was hoping we could *simplify* this, but I think it's just getting
> even more complicated (it's a net addition of 100 lines), which is due
> to feature creep that I'm afraid is my fault.
> 
> IIRC, the main thing you need is to get rid of some early memory
> allocation.
> 
> I don't think all the trigger mode/level checking is worth it.  The
> current code doesn't do it, and it's not fixing a problem for you.
> It's conceivable that it could even make us trip over a new problem,
> e.g., some broken BIOS that we currently tolerate.
> 
> I think you could make this a little easier to review if you split
> things like the acpi_irq_penalty[] -> acpi_isa_irq_penalty[] rename
> into their own patches.  Little patches like that are trivial to
> review because a simple rename is pretty safe, and then the patches
> that actually *do* interesting things are smaller and easier to
> review, too.

OK. I honestly didn't like adding this check either. I'll work on a new
set and post with your additional comments in this patch.

-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project