[ofa-general] [PATCH/RFC] IB/mthca: Remove MSI support

[Roland Dreier]

Is there any point in having MSI support in mthca, given that the
hardware also does MSI-X, which is much more useful?  Is anyone using
MSI instead of MSI-X, and if so why?

What do people think about applying this for 2.6.23?

diff --git a/drivers/infiniband/hw/mthca/mthca_dev.h b/drivers/infiniband/hw/mthca/mthca_dev.h
index 9bae3cc..1002482 100644
--- a/drivers/infiniband/hw/mthca/mthca_dev.h
+++ b/drivers/infiniband/hw/mthca/mthca_dev.h
@@ -60,7 +60,6 @@
 enum {
 	MTHCA_FLAG_DDR_HIDDEN = 1 << 1,
 	MTHCA_FLAG_SRQ        = 1 << 2,
-	MTHCA_FLAG_MSI        = 1 << 3,
 	MTHCA_FLAG_MSI_X      = 1 << 4,
 	MTHCA_FLAG_NO_LAM     = 1 << 5,
 	MTHCA_FLAG_FMR        = 1 << 6,
diff --git a/drivers/infiniband/hw/mthca/mthca_eq.c b/drivers/infiniband/hw/mthca/mthca_eq.c
index 8ec9fa1..a6ae4d9 100644
--- a/drivers/infiniband/hw/mthca/mthca_eq.c
+++ b/drivers/infiniband/hw/mthca/mthca_eq.c
@@ -842,8 +842,7 @@ int mthca_init_eq_table(struct mthca_dev *dev)
 	if (err)
 		goto err_out_free;
 
-	if (dev->mthca_flags & MTHCA_FLAG_MSI ||
-	    dev->mthca_flags & MTHCA_FLAG_MSI_X) {
+	if (dev->mthca_flags & MTHCA_FLAG_MSI_X) {
 		dev->eq_table.clr_mask = 0;
 	} else {
 		dev->eq_table.clr_mask =
@@ -854,8 +853,7 @@ int mthca_init_eq_table(struct mthca_dev *dev)
 
 	dev->eq_table.arm_mask = 0;
 
-	intr = (dev->mthca_flags & MTHCA_FLAG_MSI) ?
-		128 : dev->eq_table.inta_pin;
+	intr = dev->eq_table.inta_pin;
 
 	err = mthca_create_eq(dev, dev->limits.num_cqs + MTHCA_NUM_SPARE_EQE,
 			      (dev->mthca_flags & MTHCA_FLAG_MSI_X) ? 128 : intr,
diff --git a/drivers/infiniband/hw/mthca/mthca_main.c b/drivers/infiniband/hw/mthca/mthca_main.c
index aa563e6..f5abdbf 100644
--- a/drivers/infiniband/hw/mthca/mthca_main.c
+++ b/drivers/infiniband/hw/mthca/mthca_main.c
@@ -67,7 +67,7 @@ MODULE_PARM_DESC(msi_x, "attempt to use MSI-X if nonzero");
 
 static int msi = 0;
 module_param(msi, int, 0444);
-MODULE_PARM_DESC(msi, "attempt to use MSI if nonzero");
+MODULE_PARM_DESC(msi, "(MSI support has been removed; ignored)");
 
 #else /* CONFIG_PCI_MSI */
 
@@ -837,7 +837,7 @@ static int mthca_setup_hca(struct mthca_dev *dev)
 			  dev->mthca_flags & MTHCA_FLAG_MSI_X ?
 			  dev->eq_table.eq[MTHCA_EQ_CMD].msi_x_vector :
 			  dev->pdev->irq);
-		if (dev->mthca_flags & (MTHCA_FLAG_MSI | MTHCA_FLAG_MSI_X))
+		if (dev->mthca_flags & 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");
@@ -1117,9 +1117,8 @@ static int __mthca_init_one(struct pci_dev *pdev, int hca_type)
 
 	if (msi_x && !mthca_enable_msi_x(mdev))
 		mdev->mthca_flags |= MTHCA_FLAG_MSI_X;
-	if (msi && !(mdev->mthca_flags & MTHCA_FLAG_MSI_X) &&
-	    !pci_enable_msi(pdev))
-		mdev->mthca_flags |= MTHCA_FLAG_MSI;
+	if (msi)
+		mthca_warn(mdev, "MSI support has been removed; msi flag is ignored.\n");
 
 	if (mthca_cmd_init(mdev)) {
 		mthca_err(mdev, "Failed to init command interface, aborting.\n");
@@ -1188,8 +1187,6 @@ err_cmd:
 err_free_dev:
 	if (mdev->mthca_flags & MTHCA_FLAG_MSI_X)
 		pci_disable_msix(pdev);
-	if (mdev->mthca_flags & MTHCA_FLAG_MSI)
-		pci_disable_msi(pdev);
 
 	ib_dealloc_device(&mdev->ib_dev);
 
@@ -1236,8 +1233,6 @@ static void __mthca_remove_one(struct pci_dev *pdev)
 
 		if (mdev->mthca_flags & MTHCA_FLAG_MSI_X)
 			pci_disable_msix(pdev);
-		if (mdev->mthca_flags & MTHCA_FLAG_MSI)
-			pci_disable_msi(pdev);
 
 		ib_dealloc_device(&mdev->ib_dev);
 		mthca_release_regions(pdev, mdev->mthca_flags &