Hi Mateusz, On Tue, 26 Dec 2023 13:42:54 +0100, Mateusz Jończyk 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> I'm still happy with this patch, so you can change that back to: Reviewed-by: Jean Delvare <jdelvare@xxxxxxx> Tested-by: Jean Delvare <jdelvare@xxxxxxx> Thanks, -- Jean Delvare SUSE L3 Support
