PCI: add infrastructure for devices with broken INTx masking

pci_intx_mask_supported() assumes INTx masking is supported if the
PCI_COMMAND_INTX_DISABLE bit is writable.  But when that bit is set,
some devices don't actually mask INTx or update PCI_STATUS_INTERRUPT
as we expect.

This patch adds a way for quirks to identify these broken devices.

[bhelgaas: split out from Chelsio quirk addition]
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

3 files changed, 14 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 447e83472c01..9ae517a68360 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2876,6 +2876,9 @@ bool pci_intx_mask_supported(struct pci_dev *dev)
         bool mask_supported = false;
         u16 orig, new;
 
+        if (dev->broken_intx_masking)
+                return false;
+
         pci_cfg_access_lock(dev);
 
         pci_read_config_word(dev, PCI_COMMAND, &orig);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 2a7521677541..cc13415416d7 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2929,6 +2929,16 @@ static void __devinit disable_igfx_irq(struct pci_dev *dev)
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x0102, disable_igfx_irq);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x010a, disable_igfx_irq);
 
+/*
+ * Some devices may pass our check in pci_intx_mask_supported if
+ * PCI_COMMAND_INTX_DISABLE works though they actually do not properly
+ * support this feature.
+ */
+static void __devinit quirk_broken_intx_masking(struct pci_dev *dev)
+{
+        dev->broken_intx_masking = 1;
+}
+
 static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
                           struct pci_fixup *end)
 {
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d8c379dba6ad..40a039f1dffb 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -324,6 +324,7 @@ struct pci_dev {
         unsigned int    is_hotplug_bridge:1;
         unsigned int    __aer_firmware_first_valid:1;
         unsigned int    __aer_firmware_first:1;
+        unsigned int    broken_intx_masking:1;
         pci_dev_flags_t dev_flags;
         atomic_t        enable_cnt;     /* pci_enable_device has been called */