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authorLinus Torvalds <torvalds@linux-foundation.org>2019-07-19 00:07:03 +0000
committerJohannes Weiner <hannes@cmpxchg.org>2019-07-19 00:07:03 +0000
commitcaf0636602dedec81f71a906a5e67b1ea736f39a (patch)
tree7d88f0c28d1cbcd4ad3173ad6c90149b23675868
parent2e3d3ffe0b3ce16f87d7aa7830029acd94866aa8 (diff)
pci: test for unexpectedly disabled bridgesv5.2-mmotm-2019-07-18-16-08
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 29ed5ec1ac27..64814986a547 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1341,6 +1341,15 @@ static void pci_restore_ltr_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]);