pci_pcie_cap invalid on AER/EEH enabled PPC?

Jon Mason jdmason at kudzu.us
Sat Jul 2 01:24:05 EST 2011

I recently sent out a number of patches to migrate drivers calling
`pci_find_capability(pdef, PCI_CAP_ID_EXP)` to pci_pcie_cap.  This
function takes uses a PCI-E capability offset that was determined by
calling pci_find_capability during the PCI bus walking.  In response
to one of the patches, James Smart posted:

"The reason is due to an issue on PPC platforms whereby use of
"pdev->is_pcie" and pci_is_pcie() will erroneously fail under some
conditions, but explicit search for the capability struct via
pci_find_capability() is always successful.   I expect this to be due
a shadowing of pci config space in the hal/platform that isn't
sufficiently built up.  We detected this issue while testing AER/EEH,
and are functional only if the pci_find_capability() option is used."

See http://marc.info/?l=linux-scsi&m=130946649427828&w=2 for the whole post.

Based on his description above pci_pcie_cap
andpci_find_capability(pdef, PCI_CAP_ID_EXP) should be functionally
equivalent.  If this is not safe, then the PCI bus walking code is
most likely busted on EEH enabled PPC systems (and that is a BIG
problem).  Can anyone confirm this is still an issue?


More information about the Linuxppc-dev mailing list