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authorLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 07:05:08 +0000
committerJohannes Weiner <hannes@cmpxchg.org>2018-08-22 07:05:08 +0000
commit10b78d76f1897885d7753586ecd113e9d6728c5d (patch)
tree26715d4f17f32b3f263ab218e1fb271e0957cc3a
parenta516f76d49105f2c4661a0d338cc80800b2e4a6c (diff)
pci: test for unexpectedly disabled bridgesv4.18-mmotm-2018-08-21-23-23
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 29ff9619b5fa..f64b989140a7 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1271,6 +1271,15 @@ 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]);