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authorLinus Torvalds <torvalds@linux-foundation.org>2018-04-06 01:07:36 +0000
committerJohannes Weiner <hannes@cmpxchg.org>2018-04-06 01:07:36 +0000
commitb3cb758191e277309596782a5c8e8c8795bf083b (patch)
tree1b715121124513d863452332725091a74bdb2698
parentf6bcbf5970cd0ad5b25c4e29b7081fede66e5e7b (diff)
pci: test for unexpectedly disabled bridgesv4.16-mmotm-2018-04-05-16-59
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 aa86e904f93c..80d12e47ff1b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1099,6 +1099,15 @@ 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]);