[PATCH] InfiniBand/mthca: test IRQ routing during initialization

When we switch to interrupt-driven command mode, test interrupt generation
with a NOP firmware command.  Broken MSI/MSI-X and interrupt line routing
problems seem to be very common, and this makes the error message much clearer
-- before this change we would mysteriously fail when initializing the QP
table.
Signed-off-by: Roland Dreier <roland@topspin.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/infiniband/hw/mthca/mthca_cmd.c

@@ -1757,3 +1757,8 @@ int mthca_MGID_HASH(struct mthca_dev *dev, void *gid, u16 *hash,
 	pci_unmap_single(dev->pdev, indma, 16, PCI_DMA_TODEVICE);
 	return err;
 }
+
+int mthca_NOP(struct mthca_dev *dev, u8 *status)
+{
+	return mthca_cmd(dev, 0, 0x1f, 0, CMD_NOP, msecs_to_jiffies(100), status);
+}

drivers/infiniband/hw/mthca/mthca_cmd.h

@@ -289,6 +289,7 @@ int mthca_WRITE_MGM(struct mthca_dev *dev, int index, void *mgm,
 		    u8 *status);
 int mthca_MGID_HASH(struct mthca_dev *dev, void *gid, u16 *hash,
 		    u8 *status);
+int mthca_NOP(struct mthca_dev *dev, u8 *status);
 
 #define MAILBOX_ALIGN(x) ((void *) ALIGN((unsigned long) (x), MTHCA_CMD_MAILBOX_ALIGN))
 

drivers/infiniband/hw/mthca/mthca_main.c

@@ -570,6 +570,7 @@ static int __devinit mthca_init_hca(struct mthca_dev *mdev)
 static int __devinit mthca_setup_hca(struct mthca_dev *dev)
 {
 	int err;
+	u8 status;
 
 	MTHCA_INIT_DOORBELL_LOCK(&dev->doorbell_lock);
 
@@ -615,6 +616,18 @@ static int __devinit mthca_setup_hca(struct mthca_dev *dev)
 		goto err_eq_table_free;
 	}
 
+	err = mthca_NOP(dev, &status);
+	if (err || status) {
+		mthca_err(dev, "NOP command failed to generate interrupt, aborting.\n");
+		if (dev->mthca_flags & (MTHCA_FLAG_MSI | MTHCA_FLAG_MSI_X))
+			mthca_err(dev, "Try again with MSI/MSI-X disabled.\n");
+		else
+			mthca_err(dev, "BIOS or ACPI interrupt routing problem?\n");
+
+		goto err_cmd_poll;
+	} else
+		mthca_dbg(dev, "NOP command IRQ test passed\n");
+
 	err = mthca_init_cq_table(dev);
 	if (err) {
 		mthca_err(dev, "Failed to initialize "