Subject: strange PCI resource behaviour in 2.4

From: David Monro <[email-masked]>
Date: Thu, 24 Aug 2000 02:03:19 +0100

Hi,

I'm seeing a strange problem with the PCI code on 2.4. What is happening
is that the PCI code seems to be detecting a memory region on my pcnet32
chip, but leaving it at 0x0:

prozac:~# lspci -v -vv -s 0c
00:0c.0 Ethernet controller: Advanced Micro Devices [AMD] 79c970 [PCnet
LANCE] (rev 16)
	Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B-
	Status: Cap- 66Mhz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
	Interrupt: pin A routed to IRQ 15
	Region 0: I/O ports at 1000200 [disabled] [size=32]
	Region 1: Memory at <unassigned> (32-bit, non-prefetchable) [disabled]
[size=32]
	Expansion ROM at <unassigned> [disabled] [size=64K]

(On a 2.2 kernel, Region 1 and the Expansion ROM simply aren't there,
presumably bacuse the firmware doesn't enable them.)

This means when the device driver calls pci_enable_device, it doesn't
work.

excerpt from dmesg:
pcnet32_probe_pci: found device 0x001022.0x002000
  ioaddr=0x1000200  resource_flags=0x000101
PCI: Device 00:0c.0 not available because of resource collisions
pcnet32.c: failed to enable device -- err=-22

This is because the code in pcibios_enable_device() checks for the
combination of a region with a base of 0 and a non-0 end and fails if
that is the case.

I guess this is a consequence of the new code which searches for pci
regions rather then just accepting what the bios gives it. Should I make
it assign a sensible base address to the regions it finds, or fix it so
that the end address is also 0 if the start address is left at 0? Where
should the fix go? Note that I don't get any "PCI: Address space
collision on region ..." messages while booting, so the initialization
code doesn't seem to think there is a problem at any stage.

This is using an IBM 850.

Cheers,

	Davvid

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/