[SCSI] ipr: Remove unnecessary interrupt clearing on new adapters

The latest ipr hardware no longer requires the driver to issue any MMIOs
to clear the interrupt so remove this to optimize performance.
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/ipr.c

@@ -105,6 +105,7 @@ static const struct ipr_chip_cfg_t ipr_chip_cfg[] = {
 	{ /* Gemstone, Citrine, Obsidian, and Obsidian-E */
 		.mailbox = 0x0042C,
 		.cache_line_size = 0x20,
+		.clear_isr = 1,
 		{
 			.set_interrupt_mask_reg = 0x0022C,
 			.clr_interrupt_mask_reg = 0x00230,
@@ -127,6 +128,7 @@ static const struct ipr_chip_cfg_t ipr_chip_cfg[] = {
 	{ /* Snipe and Scamp */
 		.mailbox = 0x0052C,
 		.cache_line_size = 0x20,
+		.clear_isr = 1,
 		{
 			.set_interrupt_mask_reg = 0x00288,
 			.clr_interrupt_mask_reg = 0x0028C,
@@ -149,6 +151,7 @@ static const struct ipr_chip_cfg_t ipr_chip_cfg[] = {
 	{ /* CRoC */
 		.mailbox = 0x00044,
 		.cache_line_size = 0x20,
+		.clear_isr = 0,
 		{
 			.set_interrupt_mask_reg = 0x00010,
 			.clr_interrupt_mask_reg = 0x00018,
@@ -5049,12 +5052,14 @@ static irqreturn_t ipr_handle_other_interrupt(struct ipr_ioa_cfg *ioa_cfg,
 		del_timer(&ioa_cfg->reset_cmd->timer);
 		ipr_reset_ioa_job(ioa_cfg->reset_cmd);
 	} else if ((int_reg & IPR_PCII_HRRQ_UPDATED) == int_reg) {
-		if (ipr_debug && printk_ratelimit())
-			dev_err(&ioa_cfg->pdev->dev,
-				"Spurious interrupt detected. 0x%08X\n", int_reg);
-		writel(IPR_PCII_HRRQ_UPDATED, ioa_cfg->regs.clr_interrupt_reg32);
-		int_reg = readl(ioa_cfg->regs.sense_interrupt_reg32);
-		return IRQ_NONE;
+		if (ioa_cfg->clear_isr) {
+			if (ipr_debug && printk_ratelimit())
+				dev_err(&ioa_cfg->pdev->dev,
+					"Spurious interrupt detected. 0x%08X\n", int_reg);
+			writel(IPR_PCII_HRRQ_UPDATED, ioa_cfg->regs.clr_interrupt_reg32);
+			int_reg = readl(ioa_cfg->regs.sense_interrupt_reg32);
+			return IRQ_NONE;
+		}
 	} else {
 		if (int_reg & IPR_PCII_IOA_UNIT_CHECKED)
 			ioa_cfg->ioa_unit_checked = 1;
@@ -5154,6 +5159,9 @@ static irqreturn_t ipr_isr(int irq, void *devp)
 			}
 		}
 
+		if (ipr_cmd && !ioa_cfg->clear_isr)
+			break;
+
 		if (ipr_cmd != NULL) {
 			/* Clear the PCI interrupt */
 			num_hrrq = 0;
@@ -8769,6 +8777,7 @@ static int __devinit ipr_probe_ioa(struct pci_dev *pdev,
 	/* set SIS 32 or SIS 64 */
 	ioa_cfg->sis64 = ioa_cfg->ipr_chip->sis_type == IPR_SIS64 ? 1 : 0;
 	ioa_cfg->chip_cfg = ioa_cfg->ipr_chip->cfg;
+	ioa_cfg->clear_isr = ioa_cfg->chip_cfg->clear_isr;
 
 	if (ipr_transop_timeout)
 		ioa_cfg->transop_timeout = ipr_transop_timeout;

drivers/scsi/ipr.h

@@ -1306,6 +1306,7 @@ struct ipr_interrupts {
 struct ipr_chip_cfg_t {
 	u32 mailbox;
 	u8 cache_line_size;
+	u8 clear_isr;
 	struct ipr_interrupt_offsets regs;
 };
 
@@ -1388,6 +1389,7 @@ struct ipr_ioa_cfg {
 	u8 sis64:1;
 	u8 dump_timeout:1;
 	u8 cfg_locked:1;
+	u8 clear_isr:1;
 
 	u8 revid;