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authorLinus Torvalds <torvalds@linux-foundation.org>2019-09-04 05:02:55 +0000
committerJohannes Weiner <hannes@cmpxchg.org>2019-09-04 05:02:55 +0000
commit8619f9b5bbcc5d1b1f9ce44d1beeb6c991782ea6 (patch)
treee41ba74faf1740a4a1dfcf01d1f23b5479172845
parent28be787b59403ca877de2d4b55cc8487d67d4b0e (diff)
pci: test for unexpectedly disabled bridgesHEADv5.3-rc7-mmots-2019-09-03-21-33master
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 484e35349565..91536929abcc 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]);