[PATCH 2/3] x86/PCI: Include function number in $PIR table dump

From: Maciej W. Rozycki
Date: Fri Jun 25 2021 - 05:23:30 EST


Contrary to the PCI BIOS specification[1] some systems include the PCI
function number for motherboard devices in their $PIR table, e.g. this
is what the Tyan Tomcat IV S1564D board reports:

00:14 slot=01
0:60/deb8
1:61/deb8
2:62/deb8
3:63/deb8

00:13 slot=02
0:61/deb8
1:62/deb8
2:63/deb8
3:60/deb8

00:12 slot=03
0:62/deb8
1:63/deb8
2:60/deb8
3:61/deb8

00:11 slot=04
0:63/deb8
1:60/deb8
2:61/deb8
3:62/deb8

00:07 slot=00
0:00/deb8
1:00/deb8
2:00/deb8
3:00/deb8

00:07 slot=00
0:00/deb8
1:00/deb8
2:00/deb8
3:63/deb8

Print the function number then in the debug $PIR table dump:

00:14.0 slot=01
0:60/deb8
1:61/deb8
2:62/deb8
3:63/deb8

00:13.0 slot=02
0:61/deb8
1:62/deb8
2:63/deb8
3:60/deb8

00:12.0 slot=03
0:62/deb8
1:63/deb8
2:60/deb8
3:61/deb8

00:11.0 slot=04
0:63/deb8
1:60/deb8
2:61/deb8
3:62/deb8

00:07.1 slot=00
0:00/deb8
1:00/deb8
2:00/deb8
3:00/deb8

00:07.2 slot=00
0:00/deb8
1:00/deb8
2:00/deb8
3:63/deb8

References:

[1] "PCI BIOS Specification", Revision 2.1, PCI Special Interest Group,
August 26, 1994, Table 4-1 "Layout of IRQ routing table entry.", p.
12

Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
---
arch/x86/pci/irq.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

linux-x86-debug-pirq-fn.diff
Index: linux-macro-ide/arch/x86/pci/irq.c
===================================================================
--- linux-macro-ide.orig/arch/x86/pci/irq.c
+++ linux-macro-ide/arch/x86/pci/irq.c
@@ -129,7 +129,8 @@ static void __init pirq_peer_trick(void)
#ifdef DEBUG
{
int j;
- DBG(KERN_DEBUG "%02x:%02x slot=%02x", e->bus, e->devfn/8, e->slot);
+ DBG(KERN_DEBUG "%02x:%02x.%x slot=%02x",
+ e->bus, e->devfn / 8, e->devfn % 8, e->slot);
for (j = 0; j < 4; j++)
DBG(" %d:%02x/%04x", j, e->irq[j].link, e->irq[j].bitmap);
DBG("\n");