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authorLinus Torvalds <torvalds@linux-foundation.org>2016-05-24 00:04:40 +0000
committerJohannes Weiner <hannes@cmpxchg.org>2016-05-24 00:04:40 +0000
commit60a614982a2f8e07c1d61196737ac66d09138695 (patch)
treeef3ec7fea918290b5ef3f4c94c20c27c6678053a
parenta548cdf7cdc58ef627cf6f3b81a93f891bbc4227 (diff)
pci: test for unexpectedly disabled bridgesv4.6-mmotm-2016-05-23-16-51
The all-ones value is not just a "device didn't exist" case, it's also potentially a quite valid value, so not restoring it would be wrong. What *would* be interesting is to hear where the bad values came from in the first place. It sounds like the device state is saved after the PCI bus controller in front of the device has been crapped on, resulting in the PCI config cycles never reaching the device at all. Something along this patch (together with suspend/resume debugging output) migth help pinpoint it. But it really sounds like something totally brokenly turned off the PCI bridge (some ACPI shutdown crud? I wouldn't be entirely surprised) Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--drivers/pci/pci.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index c8b4dbdd1bdd..1ee0d01fce6b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1049,6 +1049,15 @@ static void pci_restore_pcix_state(struct pci_dev *dev)
int pci_save_state(struct pci_dev *dev)
{
int i;
+ u32 val;
+
+ /* Unable to read PCI device/manufacturer state? Something is seriously wrong! */
+ if (pci_read_config_dword(dev, 0, &val) || val == 0xffffffff) {
+ printk("Broken read from PCI device %s\n", pci_name(dev));
+ WARN_ON(1);
+ return -1;
+ }
+
/* XXX: 100% dword access ok here? */
for (i = 0; i < 16; i++)
pci_read_config_dword(dev, i * 4, &dev->saved_config_space[i]);