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32136568a9
I've encountered a serious problem with PCI config space access on Au1x000
platforms with recent 2.6.x-kernel. With 2.4.31 the same hardware works fine.
So I was looking for the differences:
Symptoms:
- no PCI-device is seen on bootup though two or three cards are present
- lspci output is empty
- OR: lspci shows 20 times the same device
(- OR: in some slot-configurations it worked anyhow)
System(s):
1. platform with Au1500 and three PCI-devices (actually a mycable XXS1500
with backplane for three PCI-devices)
2. platform with Au1550 and two PCI-devices (custom board)
Debugging:
I digged down to the config_access() of the au1xxx-processors in
arch/mips/pci/ops-au1000.c and switched on DEBUG.
The code of config_access() seems to be almost the same as of the
2.4.x-kernel. But the "pci_cfg_vm->addr" returned by get_vm_area(0x2000, 0)
once on booting is different. That's of course not forbidden. But the
alignment seems to be wrong. In my case, I received:
2.4.31: pci_cfg_vm->addr = c0000000
2.6.18-rc5: pci_cfg_vm->addr = c0101000
To make it short: With 2.6.x it fails on the first config-access with:
"PCI ERR detected: status 83a00356".
Fixup:
My fix is now, to use the VM_IOREMAP-flag in the get_vm_area call. This flag
seems to be introduced in mm/vmalloc.c a long time ago (in 2.6.7-bk13, I
found in gitweb).
Now, the returned address is pci_cfg_vm->addr = c0104000 and everything works
fine.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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| .. | ||
| arc | ||
| au1000 | ||
| basler/excite | ||
| boot | ||
| cobalt | ||
| configs | ||
| ddb5xxx | ||
| dec | ||
| emma2rh | ||
| galileo-boards/ev96100 | ||
| gt64120 | ||
| ite-boards | ||
| jazz | ||
| jmr3927 | ||
| kernel | ||
| lasat | ||
| lib | ||
| lib-32 | ||
| lib-64 | ||
| math-emu | ||
| mips-boards | ||
| mm | ||
| momentum | ||
| oprofile | ||
| pci | ||
| philips/pnx8550 | ||
| pmc-sierra | ||
| qemu | ||
| sgi-ip22 | ||
| sgi-ip27 | ||
| sgi-ip32 | ||
| sibyte | ||
| sni | ||
| tx4927 | ||
| tx4938 | ||
| vr41xx | ||
| defconfig | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||