diff options
| author | Dean Nelson <dnelson@redhat.com> | 2010-06-29 18:12:05 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-10 10:20:38 -0700 |
| commit | 8f0857bb563ee091d8c44d1d7a7e4f7696f364e0 (patch) | |
| tree | 577cfdd41d57d8ae6613050ce2ebb734738378c1 | |
| parent | 2b5b7a33f887c32a7506cd77ee21627a89c3e5a3 (diff) | |
e1000e: don't inadvertently re-set INTX_DISABLE
commit 36f2407fe52c55566221f8c68c8fb808abffd2f5 upstream.
Should e1000_test_msi() fail to see an msi interrupt, it attempts to
fallback to legacy INTx interrupts. But an error in the code may prevent
this from happening correctly.
Before calling e1000_test_msi_interrupt(), e1000_test_msi() disables SERR
by clearing the SERR bit from the just read PCI_COMMAND bits as it writes
them back out.
Upon return from calling e1000_test_msi_interrupt(), it re-enables SERR
by writing out the version of PCI_COMMAND it had previously read.
The problem with this is that e1000_test_msi_interrupt() calls
pci_disable_msi(), which eventually ends up in pci_intx(). And because
pci_intx() was called with enable set to 1, the INTX_DISABLE bit gets
cleared from PCI_COMMAND, which is what we want. But when we get back to
e1000_test_msi(), the INTX_DISABLE bit gets inadvertently re-set because
of the attempt by e1000_test_msi() to re-enable SERR.
The solution is to have e1000_test_msi() re-read the PCI_COMMAND bits as
part of its attempt to re-enable SERR.
During debugging/testing of this issue I found that not all the systems
I ran on had the SERR bit set to begin with. And on some of the systems
the same could be said for the INTX_DISABLE bit. Needless to say these
latter systems didn't have a problem falling back to legacy INTx
interrupts with the code as is.
Signed-off-by: Dean Nelson <dnelson@redhat.com>
Tested-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/net/e1000e/netdev.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c index 433f4dde9ea8..d177a02dd201 100644 --- a/drivers/net/e1000e/netdev.c +++ b/drivers/net/e1000e/netdev.c @@ -3073,13 +3073,18 @@ static int e1000_test_msi(struct e1000_adapter *adapter) /* disable SERR in case the MSI write causes a master abort */ pci_read_config_word(adapter->pdev, PCI_COMMAND, &pci_cmd); - pci_write_config_word(adapter->pdev, PCI_COMMAND, - pci_cmd & ~PCI_COMMAND_SERR); + if (pci_cmd & PCI_COMMAND_SERR) + pci_write_config_word(adapter->pdev, PCI_COMMAND, + pci_cmd & ~PCI_COMMAND_SERR); err = e1000_test_msi_interrupt(adapter); - /* restore previous setting of command word */ - pci_write_config_word(adapter->pdev, PCI_COMMAND, pci_cmd); + /* re-enable SERR */ + if (pci_cmd & PCI_COMMAND_SERR) { + pci_read_config_word(adapter->pdev, PCI_COMMAND, &pci_cmd); + pci_cmd |= PCI_COMMAND_SERR; + pci_write_config_word(adapter->pdev, PCI_COMMAND, pci_cmd); + } /* success ! */ if (!err) |