2.6.21rc suspend to ram regression on Lenovo X60

[Dave Jones <davej@redhat.com>]

I spent considerable time over the last day or so bisecting to
find out why an X60 stopped resuming somewhen between 2.6.20 and current -git.
(Total lockup, black screen of death).

The bisect log looked like this.

git-bisect start
# bad: [c8f71b01a50597e298dc3214a2f2be7b8d31170c] Linux 2.6.21-rc1
git-bisect bad c8f71b01a50597e298dc3214a2f2be7b8d31170c
# good: [fa285a3d7924a0e3782926e51f16865c5129a2f7] Linux 2.6.20
git-bisect good fa285a3d7924a0e3782926e51f16865c5129a2f7
# bad: [574009c1a895aeeb85eaab29c235d75852b09eb8] Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus
git-bisect bad 574009c1a895aeeb85eaab29c235d75852b09eb8
# bad: [43187902cbfafe73ede0144166b741fb0f7d04e1] Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/driver-2.6
git-bisect bad 43187902cbfafe73ede0144166b741fb0f7d04e1
# good: [1545085a28f226b59c243f88b82ea25393b0d63f] drm: Allow for 44 bit user-tokens (or drm_file offsets)
git-bisect good 1545085a28f226b59c243f88b82ea25393b0d63f
# good: [c96e2c92072d3e78954c961f53d8c7352f7abbd7] Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/usb-2.6
git-bisect good c96e2c92072d3e78954c961f53d8c7352f7abbd7
# good: [31c56d820e03a2fd47f81d6c826f92caf511f9ee] [POWERPC] pasemi: iommu support
git-bisect good 31c56d820e03a2fd47f81d6c826f92caf511f9ee
# bad: [78149df6d565c36675463352d0bfe0000b02b7a7] Merge master.kernel.org:/pub/scm/linux/kernel/git/gregkh/pci-2.6
git-bisect bad 78149df6d565c36675463352d0bfe0000b02b7a7
# good: [3d9c18872fa1db5c43ab97d8cbca43775998e49c] shpchp: remove CONFIG_HOTPLUG_PCI_SHPC_POLL_EVENT_MODE
git-bisect good 3d9c18872fa1db5c43ab97d8cbca43775998e49c
# good: [88187dfa4d8bb565df762f272511d2c91e427e0d] MSI: Replace pci_msi_quirk with calls to pci_no_msi()
git-bisect good 88187dfa4d8bb565df762f272511d2c91e427e0d
# good: [866a8c87c4e51046602387953bbef76992107bcb] msi: Fix msi_remove_pci_irq_vectors.
git-bisect good 866a8c87c4e51046602387953bbef76992107bcb
# good: [f7feaca77d6ad6bcfcc88ac54e3188970448d6fe] msi: Make MSI useable more architectures
git-bisect good f7feaca77d6ad6bcfcc88ac54e3188970448d6fe
# good: [14719f325e1cd4ff757587e9a221ebaf394563ee] Revert "PCI: remove duplicate device id from ata_piix"
git-bisect good 14719f325e1cd4ff757587e9a221ebaf394563ee

which led me to a final 'bad' commit of 78149df6d565c36675463352d0bfe0000b02b7a7
which is a merge changeset of lots of PCI bits.
Seeing a couple of MSI changes in there, on a hunch I booted latest tree with
pci=nomsi, and it resumed again.

Any ideas how to further debug this?
I'll try backing out individual changes from that merge tomorrow.

	Dave

-- 
http://www.codemonkey.org.uk