Bug 2520

Summary: interrupt source override ineffective - ES7000
Product: ACPI Reporter: Len Brown (lenb)
Component: Config-InterruptsAssignee: Len Brown (lenb)
Status: CLOSED CODE_FIX    
Severity: normal CC: acpi-bugzilla, protasnb
Priority: P2    
Hardware: i386   
OS: Linux   
Kernel Version: 2.6.5 Subsystem:
Regression: --- Bisected commit-id:
Attachments: 2.6.5 (i386 only) patch

Description Len Brown 2004-04-15 21:35:07 UTC 
Natalie Protasevich reports: 
 
"mp_override_legacy_irq() parses ACPI INT_SRC_OVR entries, 
and each override entry results in a change of corresponding mp_irqs[] array element. 
 
The problem happens when the dest_irq (pin) numerically smaller than the bus irq 
and is assigned higher array element (we index of the srcbus_irq) that the original bus irq 
with default correspondence. The mp_irqs[] element with new bus irq gets changed allright, 
but there is still the original (unmodified) element with default one-to-one assignment above it in 
the array. 
 
Int: mp_irq 12, type 0, pol 0, trig 0, bus 0, irq 13, 129-13 <-- original entry for bus irq (and pin) 13 
Int: mp_irq 13, type 0, pol 1, trig 1, bus 0, irq 14, 129-15 
Int: mp_irq 14, type 0, pol 1, trig 1, bus 0, irq 15, 129-13 <-- modified entry for bus irq 15, with 
override for pin 13 
 
Since it is a valid entry, find_irq_entry() in setup_IO_APIC_irqs() searches the mp_irqs[] 
by the pin number and runs into this element first. It uses it to program the pin and never 
gets to the element down below that contains modified entry with a correct overwrite in it."
Comment 1 Len Brown 2004-04-15 21:49:53 UTC 
Created attachment 2608 [details]
2.6.5 (i386 only) patch

The solution is to reverse the order that we initialize mp_irqs[].
ie. parse the overrides first, and then only add identity mappings
where both IRQ-N and pin-N are available to form an identity mapping.
Since there will be no duplicate entries, find_irq_entry() will
find the correct entry when it searches by pin number.
Comment 2 Len Brown 2004-05-11 23:27:20 UTC 
shipped in 2.6.6, and on top of 2.4.27-pre2 -- closing.