Re: [Patch v1] x86, ACPI, irq: Fix a regression caused by
From: Thomas Gleixner
Date: Tue Aug 18 2015 - 15:37:01 EST
On Sun, 9 Aug 2015, Jiang Liu wrote:
> Nick Meier reported a regression with HyperV that "
> After rebooting the VM, the following messages are logged in syslog
> when trying to load the tulip driver:
> tulip: Linux Tulip drivers version 1.1.15 (Feb 27, 2007)
> tulip: 0000:00:0a.0: PCI INT A: failed to register GSI
> tulip: Cannot enable tulip board #0, aborting
> tulip: probe of 0000:00:0a.0 failed with error -16
> Errors occur in 3.19.0 kernel
> Works in 3.17 kernel.
> "
>
> According to the ACPI dump file posted by Nick at
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1440072
>
> The ACPI MADT table includes an interrupt source overridden entry for
> ACPI SCI:
> [236h 0566 1] Subtable Type : 02 <Interrupt Source Override>
> [237h 0567 1] Length : 0A
> [238h 0568 1] Bus : 00
> [239h 0569 1] Source : 09
> [23Ah 0570 4] Interrupt : 00000009
> [23Eh 0574 2] Flags (decoded below) : 000D
> Polarity : 1
> Trigger Mode : 3
> That means ACPI SCI interrupt(Interrupt : 00000009) works in
> level(Trigger Mode : 3), high(Polarity : 1) mode.
>
> And in DSDT table, we have _PRT method to define PCI interrupts, which
> eventually goes to:
> Name (PRSA, ResourceTemplate ()
> {
> IRQ (Level, ActiveLow, Shared, )
> {3,4,5,7,9,10,11,12,14,15}
> })
> Name (PRSB, ResourceTemplate ()
> {
> IRQ (Level, ActiveLow, Shared, )
> {3,4,5,7,9,10,11,12,14,15}
> })
> Name (PRSC, ResourceTemplate ()
> {
> IRQ (Level, ActiveLow, Shared, )
> {3,4,5,7,9,10,11,12,14,15}
> })
> Name (PRSD, ResourceTemplate ()
> {
> IRQ (Level, ActiveLow, Shared, )
> {3,4,5,7,9,10,11,12,14,15}
> })
> which means it's also possible to use IRQ9 for PCI interrupt, but works
> in Level, ActiveLow mode. So it conflicts with ACPI SCI interrupt source
> overriddern.
>
> So implement a quirk to correct interrupt attribute for HyperV SCI
> interrupt. Nick reports the proposed patch fixes the regression as "
> Applied the above proposed patch with the DMI values substituted.
> The tulip driver loaded, and an address was assigned via DHCP.
> "
> Please refer to following links for more information:
> https://bugzilla.kernel.org/show_bug.cgi?id=101301
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1440072
>
> Fixes: cd68f6bd53cf ("x86, irq, acpi: Get rid of special handling of GSI for ACPI SCI")
I have a hard time to understand WHY that particular patch actually
caused that regression, WHY the original code worked with this weird
ACPI table and WHY we are better off with a quirk for this case.
Can you please elaborate?
Thanks,
tglx
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