[PATCH] x86/PCI: Handle IRQ swizzling with PIRQ routers

From: Maciej W. Rozycki
Date: Wed Jul 07 2021 - 08:30:55 EST

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Similarly to MP-tables PIRQ routing tables may not list devices behind
PCI-to-PCI bridges, leading to interrupt routing failures, e.g.:

pci 0000:00:07.0: PIIX/ICH IRQ router [8086:7000]
pci 0000:02:00.0: ignoring bogus IRQ 255
pci 0000:02:01.0: ignoring bogus IRQ 255
pci 0000:02:02.0: ignoring bogus IRQ 255
pci 0000:04:00.0: ignoring bogus IRQ 255
pci 0000:04:00.3: ignoring bogus IRQ 255
pci 0000:00:11.0: PCI INT A -> PIRQ 63, mask deb8, excl 0c20
pci 0000:00:11.0: PCI INT A -> newirq 0
PCI: setting IRQ 11 as level-triggered
pci 0000:00:11.0: found PCI INT A -> IRQ 11
pci 0000:00:11.0: sharing IRQ 11 with 0000:00:07.2
pci 0000:02:00.0: PCI INT A not found in routing table
pci 0000:02:01.0: PCI INT A not found in routing table
pci 0000:02:02.0: PCI INT A not found in routing table
pci 0000:04:00.0: PCI INT A not found in routing table
pci 0000:04:00.3: PCI INT D not found in routing table
pci 0000:06:05.0: PCI INT A not found in routing table
pci 0000:06:08.0: PCI INT A not found in routing table
pci 0000:06:08.1: PCI INT B not found in routing table
pci 0000:06:08.2: PCI INT C not found in routing table

and consequently non-working devices. Since PCI-to-PCI bridges have a
standardised way of routing interrupts by the means of swizzling do it
for configurations that use a PIRQ router as well, like with APIC-based
setups, and use the determined corresponding topmost bridge's interrupt
pin assignment to route a given device's interrupt:

pci 0000:00:07.0: PIIX/ICH IRQ router [8086:7000]
pci 0000:02:00.0: ignoring bogus IRQ 255
pci 0000:02:01.0: ignoring bogus IRQ 255
pci 0000:02:02.0: ignoring bogus IRQ 255
pci 0000:04:00.0: ignoring bogus IRQ 255
pci 0000:04:00.3: ignoring bogus IRQ 255
pci 0000:00:11.0: PCI INT A -> PIRQ 63, mask deb8, excl 0c20
pci 0000:00:11.0: PCI INT A -> newirq 0
PCI: setting IRQ 11 as level-triggered
pci 0000:00:11.0: found PCI INT A -> IRQ 11
pci 0000:00:11.0: sharing IRQ 11 with 0000:00:07.2
pci 0000:02:00.0: using bridge 0000:00:11.0 INT A to get INT A
pci 0000:00:11.0: sharing IRQ 11 with 0000:02:00.0
pci 0000:02:01.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:02:02.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:04:00.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:04:00.3: using bridge 0000:00:11.0 INT A to get INT D
pci 0000:00:11.0: sharing IRQ 11 with 0000:04:00.3
pci 0000:06:05.0: using bridge 0000:00:11.0 INT D to get INT A
pci 0000:06:08.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:06:08.1: using bridge 0000:00:11.0 INT D to get INT B
pci 0000:06:08.2: using bridge 0000:00:11.0 INT A to get INT C
pci 0000:00:11.0: sharing IRQ 11 with 0000:06:08.2
pci 0000:02:01.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:02:01.0: PCI INT A -> PIRQ 60, mask deb8, excl 0c20
pci 0000:02:01.0: PCI INT A -> newirq 0
PCI: setting IRQ 10 as level-triggered
pci 0000:02:01.0: found PCI INT A -> IRQ 10
pci 0000:02:01.0: sharing IRQ 10 with 0000:00:14.0
pci 0000:02:00.0: using bridge 0000:00:11.0 INT A to get INT A
pci 0000:02:01.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:02:02.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:04:00.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:02:01.0: sharing IRQ 10 with 0000:04:00.0
pci 0000:04:00.3: using bridge 0000:00:11.0 INT A to get INT D
pci 0000:06:05.0: using bridge 0000:00:11.0 INT D to get INT A
pci 0000:06:08.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:06:08.1: using bridge 0000:00:11.0 INT D to get INT B
pci 0000:06:08.2: using bridge 0000:00:11.0 INT A to get INT C
pci 0000:02:02.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:02:02.0: PCI INT A -> PIRQ 61, mask deb8, excl 0c20
pci 0000:02:02.0: PCI INT A -> newirq 0
PCI: setting IRQ 5 as level-triggered
pci 0000:02:02.0: found PCI INT A -> IRQ 5
pci 0000:02:02.0: sharing IRQ 5 with 0000:00:13.0
pci 0000:02:00.0: using bridge 0000:00:11.0 INT A to get INT A
pci 0000:02:01.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:02:02.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:04:00.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:04:00.3: using bridge 0000:00:11.0 INT A to get INT D
pci 0000:06:05.0: using bridge 0000:00:11.0 INT D to get INT A
pci 0000:06:08.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:02:02.0: sharing IRQ 5 with 0000:06:08.0
pci 0000:06:08.1: using bridge 0000:00:11.0 INT D to get INT B
pci 0000:06:08.2: using bridge 0000:00:11.0 INT A to get INT C
pci 0000:06:05.0: using bridge 0000:00:11.0 INT D to get INT A
pci 0000:06:05.0: PCI INT A -> PIRQ 62, mask deb8, excl 0c20
pci 0000:06:05.0: PCI INT A -> newirq 0
pci 0000:06:05.0: found PCI INT A -> IRQ 5
pci 0000:06:05.0: sharing IRQ 5 with 0000:00:12.0
pci 0000:02:00.0: using bridge 0000:00:11.0 INT A to get INT A
pci 0000:02:01.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:02:02.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:04:00.0: using bridge 0000:00:11.0 INT B to get INT A
pci 0000:04:00.3: using bridge 0000:00:11.0 INT A to get INT D
pci 0000:06:05.0: using bridge 0000:00:11.0 INT D to get INT A
pci 0000:06:08.0: using bridge 0000:00:11.0 INT C to get INT A
pci 0000:06:08.1: using bridge 0000:00:11.0 INT D to get INT B
pci 0000:06:05.0: sharing IRQ 5 with 0000:06:08.1
pci 0000:06:08.2: using bridge 0000:00:11.0 INT A to get INT C

Adjust log messages accordingly.

Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
---
arch/x86/pci/irq.c | 60 +++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 47 insertions(+), 13 deletions(-)

linux-x86-pirq-swizzle-irq.diff
Index: linux-macro-ide-tty/arch/x86/pci/irq.c
===================================================================
--- linux-macro-ide-tty.orig/arch/x86/pci/irq.c
+++ linux-macro-ide-tty/arch/x86/pci/irq.c
@@ -985,7 +985,7 @@ static void __init pirq_find_router(stru
* for motherboard devices, so if a complete match is found, then give
* it precedence over a slot match.
*/
-static struct irq_info *pirq_get_info(struct pci_dev *dev)
+static struct irq_info *pirq_get_dev_info(struct pci_dev *dev)
{
struct irq_routing_table *rt = pirq_table;
int entries = (rt->size - sizeof(struct irq_routing_table)) /
@@ -1004,11 +1004,42 @@ static struct irq_info *pirq_get_info(st
return slotinfo;
}

+/*
+ * Buses behind bridges are typically not listed in the PIRQ routing table.
+ * Do the usual dance then and walk the tree of bridges up adjusting the
+ * pin number accordingly on the way until the originating root bus device
+ * has been reached and then use its routing information.
+ */
+static struct irq_info *pirq_get_info(struct pci_dev *dev, u8 *pin)
+{
+ struct pci_dev *temp_dev = dev;
+ struct irq_info *info;
+ u8 temp_pin = *pin;
+ u8 dpin = temp_pin;
+
+ info = pirq_get_dev_info(dev);
+ while (!info && temp_dev->bus->parent) {
+ struct pci_dev *bridge = temp_dev->bus->self;
+
+ temp_pin = pci_swizzle_interrupt_pin(temp_dev, temp_pin);
+ info = pirq_get_dev_info(bridge);
+ if (info)
+ dev_warn(&dev->dev,
+ "using bridge %s INT %c to get INT %c\n",
+ pci_name(bridge),
+ 'A' + temp_pin - 1, 'A' + dpin - 1);
+
+ temp_dev = bridge;
+ }
+ *pin = temp_pin;
+ return info;
+}
+
static int pcibios_lookup_irq(struct pci_dev *dev, int assign)
{
- u8 pin;
struct irq_info *info;
int i, pirq, newirq;
+ u8 dpin, pin;
int irq = 0;
u32 mask;
struct irq_router *r = &pirq_router;
@@ -1016,8 +1047,8 @@ static int pcibios_lookup_irq(struct pci
char *msg = NULL;

/* Find IRQ pin */
- pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
- if (!pin) {
+ pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &dpin);
+ if (!dpin) {
dev_dbg(&dev->dev, "no interrupt pin\n");
return 0;
}
@@ -1030,20 +1061,21 @@ static int pcibios_lookup_irq(struct pci
if (!pirq_table)
return 0;

- info = pirq_get_info(dev);
+ pin = dpin;
+ info = pirq_get_info(dev, &pin);
if (!info) {
dev_dbg(&dev->dev, "PCI INT %c not found in routing table\n",
- 'A' + pin - 1);
+ 'A' + dpin - 1);
return 0;
}
pirq = info->irq[pin - 1].link;
mask = info->irq[pin - 1].bitmap;
if (!pirq) {
- dev_dbg(&dev->dev, "PCI INT %c not routed\n", 'A' + pin - 1);
+ dev_dbg(&dev->dev, "PCI INT %c not routed\n", 'A' + dpin - 1);
return 0;
}
dev_dbg(&dev->dev, "PCI INT %c -> PIRQ %02x, mask %04x, excl %04x",
- 'A' + pin - 1, pirq, mask, pirq_table->exclusive_irqs);
+ 'A' + dpin - 1, pirq, mask, pirq_table->exclusive_irqs);
mask &= pcibios_irq_mask;

/* Work around broken HP Pavilion Notebooks which assign USB to
@@ -1085,7 +1117,7 @@ static int pcibios_lookup_irq(struct pci
newirq = i;
}
}
- dev_dbg(&dev->dev, "PCI INT %c -> newirq %d", 'A' + pin - 1, newirq);
+ dev_dbg(&dev->dev, "PCI INT %c -> newirq %d", 'A' + dpin - 1, newirq);

/* Check if it is hardcoded */
if ((pirq & 0xf0) == 0xf0) {
@@ -1113,15 +1145,17 @@ static int pcibios_lookup_irq(struct pci
return 0;
}
}
- dev_info(&dev->dev, "%s PCI INT %c -> IRQ %d\n", msg, 'A' + pin - 1, irq);
+ dev_info(&dev->dev, "%s PCI INT %c -> IRQ %d\n",
+ msg, 'A' + dpin - 1, irq);

/* Update IRQ for all devices with the same pirq value */
for_each_pci_dev(dev2) {
- pci_read_config_byte(dev2, PCI_INTERRUPT_PIN, &pin);
- if (!pin)
+ pci_read_config_byte(dev2, PCI_INTERRUPT_PIN, &dpin);
+ if (!dpin)
continue;

- info = pirq_get_info(dev2);
+ pin = dpin;
+ info = pirq_get_info(dev2, &pin);
if (!info)
continue;
if (info->irq[pin - 1].link == pirq) {

Next message: Greg Ungerer: "Re: [PATCH] m68k/coldfire: change pll var. to clk_pll"
Previous message: Sasha Levin: "Re: [PATCH 5.10 0/7] 5.10.48-rc1 review"
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