[PATCH v2] PCI: Mark INTx masking support of Chelsio T310 10GbE NIC as broken

[Jan Kiszka <jan.kiszka@web.de>]

From: Jan Kiszka <jan.kiszka@siemens.com>

According to

http://thread.gmane.org/gmane.comp.emulators.kvm.devel/91388

the T310 does not properly support INTx masking as it fails to keep the
PCI_STATUS_INTERRUPT bit updated once the interrupt is masked. Mark this
adapter as broken so that pci_intx_mask_supported won't report it as
compatible.

Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

Changes in v2:
 - Fixed device ID to Alexey's report
 - Added reference to the original report

 drivers/pci/pci.c    |    3 +++
 drivers/pci/quirks.c |   12 ++++++++++++
 include/linux/pci.h  |    2 ++
 3 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 447e834..9ae517a 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 2a75216..28804f4 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2929,6 +2929,18 @@ 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;
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CHELSIO, 0x0030,
+			quirk_broken_intx_masking);
+
 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 d8c379d..7ea6cf8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -324,6 +324,8 @@ 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;	/* device's INTx masking
+						   support is not working */
 	pci_dev_flags_t dev_flags;
 	atomic_t	enable_cnt;	/* pci_enable_device has been called */
 
-- 
1.7.3.4