@@ -203,6 +203,8 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
struct acpi_pci_routing_table *entry;
acpi_handle handle = NULL;
+ struct acpi_prt_entry *match = NULL;
+ const char *match_int_source = NULL;
if (dev->bus->bridge)
handle = ACPI_HANDLE(dev->bus->bridge);
@@ -219,13 +221,30 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
entry = buffer.pointer;
while (entry && (entry->length > 0)) {
- if (!acpi_pci_irq_check_entry(handle, dev, pin,
- entry, entry_ptr))
- break;
+ struct acpi_prt_entry *curr;
+
+ if (!acpi_pci_irq_check_entry(handle, dev, pin, entry, &curr)) {
+ if (match == NULL) {
+ match = curr;
+ match_int_source = entry->source;
+ } else {
+ pr_warn(FW_BUG
+ "ACPI _PRT returned duplicate IRQ routing entries for device "
+ "%04x:%02x:%02x[INT%c]: %s[%d] and %s[%d]. ",
+ curr->id.segment, curr->id.bus, curr->id.device,
+ pin_name(curr->pin),
+ match_int_source, match->index,
+ entry->source, curr->index);
+ // we use the first matching entry nonetheless
+ }
+ }
+
entry = (struct acpi_pci_routing_table *)
((unsigned long)entry + entry->length);
}
+ *entry_ptr = match;
+
kfree(buffer.pointer);
return 0;
}
On some platforms, the ACPI _PRT function returns duplicate interrupt routing entries. Linux uses the first matching entry, but sometimes the second matching entry contains the correct interrupt vector. To check how widespread this problem is, print a warning to dmesg if this is the case. This happens on a Dell Latitude E6500 laptop with the i2c-i801 Intel SMBus controller. This controller was nonfunctional unless its interrupt usage was disabled (using the "disable_features=0x10" module parameter). After investigation, it turned out that the driver was using an incorrect interrupt vector: in lspci output for this device there was: Interrupt: pin B routed to IRQ 19 but after running i2cdetect (without using any i2c-i801 module parameters) the following was logged to dmesg: [...] i801_smbus 0000:00:1f.3: Timeout waiting for interrupt! i801_smbus 0000:00:1f.3: Transaction timeout irq 17: nobody cared (try booting with the "irqpoll" option) Existence of duplicate entries in the table returned by the _PRT method was confirmed by disassembling the ACPI DSDT table. Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Len Brown <lenb@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: Jean Delvare <jdelvare@suse.com> --- drivers/acpi/pci_irq.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) base-commit: f0c4d9fc9cc9462659728d168387191387e903cc