![]() To find a host bridge's downstream bus number, we currently look at _BBN first. If _BBN returns a bus number we've already seen, we conclude that _BBN was wrong and look for a bus number in _CRS. However, the spec[1] (figure 5-5 and the example in sec 9.12.1) and an ACPI FAQ[2] suggest that the OS should use _CRS to discover the bus number range, and that _BBN is really intended to bootstrap _CRS methods that reference PCI opregions. This patch makes us always look at _CRS first. If _CRS doesn't supply a bus number, we look at _BBN. If _BBN doesn't exist, we default to zero. This makes the behavior consistent regardless of device discovery order. Previously, if A and B had duplicate _BBNs and we found A first, we'd only look at B's _CRS, whereas if we found B first, we'd only look at A's _CRS. I'm told that Windows discovers host bridge bus numbers using _CRS, so it should be fairly safe to rely on this BIOS functionality. This patch also removes two misleading messages: we printed the "Wrong _BBN value, reboot and use option 'pci=noacpi'" message before looking at _CRS, so we would likely find the bus number in _CRS, the system would work fine, and the user would be confused. The "PCI _CRS %d overrides _BBN 0" message incorrectly assumes _BBN was zero, and it's useless anyway because we print the segment/bus number a few lines later. References: [1] http://www.acpi.info/DOWNLOADS/ACPIspec30b.pdf [2] http://www.acpi.info/acpi_faq.htm _BBN/_CRS discussion http://download.microsoft.com/download/9/8/f/98f3fe47-dfc3-4e74-92a3-088782200fe7/TWAR05005_WinHEC05.ppt (slide 17) http://bugzilla.kernel.org/show_bug.cgi?id=1662 ASUS PR-DLS http://bugzilla.kernel.org/show_bug.cgi?id=1127 ASUS PR-DLSW http://bugzilla.kernel.org/show_bug.cgi?id=1741 ASUS PR-DLS533 Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Reviewed-by: Alex Chiang <achiang@hp.com> CC: Shaohua Li <shaohua.li@intel.com> CC: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Signed-off-by: Len Brown <len.brown@intel.com> |
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.. | ||
acpica | ||
ac.c | ||
acpi_memhotplug.c | ||
battery.c | ||
blacklist.c | ||
bus.c | ||
button.c | ||
cm_sbs.c | ||
container.c | ||
debug.c | ||
dock.c | ||
ec.c | ||
event.c | ||
fan.c | ||
glue.c | ||
internal.h | ||
Kconfig | ||
Makefile | ||
numa.c | ||
osl.c | ||
pci_bind.c | ||
pci_irq.c | ||
pci_link.c | ||
pci_root.c | ||
pci_slot.c | ||
power.c | ||
proc.c | ||
processor_core.c | ||
processor_idle.c | ||
processor_perflib.c | ||
processor_thermal.c | ||
processor_throttling.c | ||
reboot.c | ||
sbs.c | ||
sbshc.c | ||
sbshc.h | ||
scan.c | ||
sleep.c | ||
sleep.h | ||
system.c | ||
tables.c | ||
thermal.c | ||
utils.c | ||
video.c | ||
video_detect.c | ||
wakeup.c |