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authorLinus Torvalds <torvalds@linux-foundation.org>2019-08-13 23:09:38 +0000
committerJohannes Weiner <hannes@cmpxchg.org>2019-08-13 23:09:38 +0000
commit9c894e48edf24c4719c5938cc8950f30676479ef (patch)
treec10c923d1fb67abab55c5bf4fd29bf7eb11add77
parent94184bed5c924ec03e5d98df8a248e0416d46f8b (diff)
pci: test for unexpectedly disabled bridgesHEADv5.3-rc4-mmotm-2019-08-13-15-40master
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 f20a3de57d21..d1d7eba78592 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1346,6 +1346,15 @@ 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]);