PCI: Mark Atheros AR93xx to avoid bus reset

commit c3e59ee4e76686b0c84ca8faa1011d10cd4ca1b8 upstream.

Reports against the TL-WDN4800 card indicate that PCI bus reset of this
Atheros device cause system lock-ups and resets.  I've also been able to
confirm this behavior on multiple systems.  The device never returns from
reset and attempts to access config space of the device after reset result
in hangs.  Blacklist bus reset for the device to avoid this issue.

[bhelgaas: This regression appeared in v3.14.  Andreas bisected it to
425c1b223dac ("PCI: Add Virtual Channel to save/restore support"), but we
don't understand the mechanism by which that commit affects the reset
path.]

[bhelgaas: changelog, references]
Link: http://lkml.kernel.org/r/20140923210318.498dacbd@dualc.maya.org
Reported-by: Andreas Hartmann <andihartmann@freenet.de>
Tested-by: Andreas Hartmann <andihartmann@freenet.de>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 6e8776b59a2c53f527ef79d06702449ce07fc63d..27abeb40dfabadb45fee3f2c85cfb3cc29bf48ee 100644 (file)
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3008,6 +3008,20 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_CHELSIO, 0x0030,
 DECLARE_PCI_FIXUP_HEADER(0x1814, 0x0601, /* Ralink RT2800 802.11n PCI */
                         quirk_broken_intx_masking);
 
+static void quirk_no_bus_reset(struct pci_dev *dev)
+{
+       dev->dev_flags |= PCI_DEV_FLAGS_NO_BUS_RESET;
+}
+
+/*
+ * Atheros AR93xx chips do not behave after a bus reset.  The device will
+ * throw a Link Down error on AER-capable systems and regardless of AER,
+ * config space of the device is never accessible again and typically
+ * causes the system to hang or reset when access is attempted.
+ * http://www.spinics.net/lists/linux-pci/msg34797.html
+ */
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0030, quirk_no_bus_reset);
+
 static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
                          struct pci_fixup *end)
 {