On Fri, Feb 16, 2024 at 07:26:06PM +0100, Rafael J. Wysocki wrote: > 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. The usual comment style in this file is: /* * We use ... */ > > + */ > > + } > > + } > > + > > 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? No concerns from me. I guess this only adds a message, right? It doesn't actually fix anything or change any behavior? This talks about "duplicate" entries, which suggests to me that they are identical, but I don't think they are. It sounds like it's two "matching" entries, i.e., two entries for the same (device, pin)? And neither of the two _PRT entries yields a working i801 device? Bjorn
