On Tue, Dec 26, 2023 at 1:50 PM Mateusz Jończyk <mat.jonczyk@xxxxx> wrote: > > 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. > > As a debugging aid, print a warning to dmesg if duplicate interrupt > routing entries are present. This way, we could check how many models > are affected. > > This happens on a Dell Latitude E6500 laptop with the i2c-i801 Intel > SMBus controller. This controller is nonfunctional unless its interrupt > usage is 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 > 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 a table returned by the _PRT method > was confirmed by disassembling the ACPI DSDT table. > > Windows XP is using IRQ3 (as reported by HWiNFO32 and in the Device > Manager), which is neither of the two vectors returned by _PRT. > As HWiNFO32 decoded contents of the SPD EEPROMs, the i2c-i801 device is > working under Windows. It appears that Windows has reconfigured the > chipset independently to use another interrupt vector for the device. > This is possible, according to the chipset datasheet [1], page 436 for > example (PIRQ[n]_ROUT—PIRQ[A,B,C,D] Routing Control Register). > > [1] https://www.intel.com/content/dam/doc/datasheet/io-controller-hub-9-datasheet.pdf > > Signed-off-by: Mateusz Jończyk <mat.jonczyk@xxxxx> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> > Cc: Len Brown <lenb@xxxxxxxxxx> > Cc: Borislav Petkov <bp@xxxxxxx> > Cc: Jean Delvare <jdelvare@xxxxxxx> > Previously-reviewed-by: Jean Delvare <jdelvare@xxxxxxx> > Previously-tested-by: Jean Delvare <jdelvare@xxxxxxx> > > --- > Hello, > > I'm resurrecting an older patch that was discussed back in January: > > https://lore.kernel.org/lkml/20230121153314.6109-1-mat.jonczyk@xxxxx/T/#u > > To consider: should we print a warning or an error in case of duplicate > entries? This may not be serious enough to disturb the user with an > error message at boot. > > I'm also looking into modifying the i2c-i801 driver to disable its usage > of interrupts if one did not fire. > > v2: - add a newline at the end of the kernel log message, > - replace: "if (match == NULL)" -> "if (!match)" > - patch description tweaks. > v3: - fix C style issues pointed by Jean Delvare, > - switch severity from warning to error. > v3 RESEND: retested on top of v6.2-rc4 > v4: - rebase and retest on top of v6.7-rc7 > - switch severity back to warning, > - change pr_err() to dev_warn() and simplify the code, > - modify patch description (describe Windows behaviour etc.) > --- > drivers/acpi/pci_irq.c | 25 ++++++++++++++++++++++--- > 1 file changed, 22 insertions(+), 3 deletions(-) > > diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c > index ff30ceca2203..1fcf72e335b0 100644 > --- a/drivers/acpi/pci_irq.c > +++ b/drivers/acpi/pci_irq.c > @@ -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) { > + match = curr; > + match_int_source = entry->source; > + } else { > + dev_warn(&dev->dev, FW_BUG dev_info() would be sufficient here IMV. > + "ACPI _PRT returned duplicate IRQ routing entries for INT%c: %s[%d] and %s[%d]\n", > + pin_name(curr->pin), > + match_int_source, match->index, > + entry->source, curr->index); > + /* We use the first matching entry nonetheless, > + * for compatibility with older kernels. > + */ > + } > + } > + > entry = (struct acpi_pci_routing_table *) > ((unsigned long)entry + entry->length); > } > > + *entry_ptr = match; > + > kfree(buffer.pointer); > return 0; > } > > base-commit: 861deac3b092f37b2c5e6871732f3e11486f7082 > -- Bjorn, any concerns regarding this one?
