[SCSI] ipr: add workaround for MSI interrupts on P7

This patch adds some additional logic to the interrupt service routine to fix
a potential problem where an MSI interrupt does not get cleared the first time.

Signed-off-by: Wayne Boyer <wayneb@linux.vnet.ibm.com>
Acked-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

2 files changed, 34 insertions, 9 deletions

diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index 5f045505a1f4..76d294fc7846 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -4189,6 +4189,25 @@ static irqreturn_t ipr_handle_other_interrupt(struct ipr_ioa_cfg *ioa_cfg,
 }
 
 /**
+ * ipr_isr_eh - Interrupt service routine error handler
+ * @ioa_cfg:    ioa config struct
+ * @msg:        message to log
+ *
+ * Return value:
+ *      none
+ **/
+static void ipr_isr_eh(struct ipr_ioa_cfg *ioa_cfg, char *msg)
+{
+        ioa_cfg->errors_logged++;
+        dev_err(&ioa_cfg->pdev->dev, "%s\n", msg);
+
+        if (WAIT_FOR_DUMP == ioa_cfg->sdt_state)
+                ioa_cfg->sdt_state = GET_DUMP;
+
+        ipr_initiate_ioa_reset(ioa_cfg, IPR_SHUTDOWN_NONE);
+}
+
+/**
  * ipr_isr - Interrupt service routine
  * @irq:        irq number
  * @devp:       pointer to ioa config struct
@@ -4203,6 +4222,7 @@ static irqreturn_t ipr_isr(int irq, void *devp)
         volatile u32 int_reg, int_mask_reg;
         u32 ioasc;
         u16 cmd_index;
+        int num_hrrq = 0;
         struct ipr_cmnd *ipr_cmd;
         irqreturn_t rc = IRQ_NONE;
 
@@ -4233,13 +4253,7 @@ static irqreturn_t ipr_isr(int irq, void *devp)
                                      IPR_HRRQ_REQ_RESP_HANDLE_MASK) >> IPR_HRRQ_REQ_RESP_HANDLE_SHIFT;
 
                         if (unlikely(cmd_index >= IPR_NUM_CMD_BLKS)) {
-                                ioa_cfg->errors_logged++;
-                                dev_err(&ioa_cfg->pdev->dev, "Invalid response handle from IOA\n");
-
-                                if (WAIT_FOR_DUMP == ioa_cfg->sdt_state)
-                                        ioa_cfg->sdt_state = GET_DUMP;
-
-                                ipr_initiate_ioa_reset(ioa_cfg, IPR_SHUTDOWN_NONE);
+                                ipr_isr_eh(ioa_cfg, "Invalid response handle from IOA");
                                 spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
                                 return IRQ_HANDLED;
                         }
@@ -4266,8 +4280,18 @@ static irqreturn_t ipr_isr(int irq, void *devp)
 
                 if (ipr_cmd != NULL) {
                         /* Clear the PCI interrupt */
-                        writel(IPR_PCII_HRRQ_UPDATED, ioa_cfg->regs.clr_interrupt_reg);
-                        int_reg = readl(ioa_cfg->regs.sense_interrupt_reg) & ~int_mask_reg;
+                        do {
+                                writel(IPR_PCII_HRRQ_UPDATED, ioa_cfg->regs.clr_interrupt_reg);
+                                int_reg = readl(ioa_cfg->regs.sense_interrupt_reg) & ~int_mask_reg;
+                        } while (int_reg & IPR_PCII_HRRQ_UPDATED &&
+                                        num_hrrq++ < IPR_MAX_HRRQ_RETRIES);
+
+                        if (int_reg & IPR_PCII_HRRQ_UPDATED) {
+                                ipr_isr_eh(ioa_cfg, "Error clearing HRRQ");
+                                spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
+                                return IRQ_HANDLED;
+                        }
+
                 } else
                         break;
         }
diff --git a/drivers/scsi/ipr.h b/drivers/scsi/ipr.h
index 163245a1c3e5..19bbcf39f0c9 100644
--- a/drivers/scsi/ipr.h
+++ b/drivers/scsi/ipr.h
@@ -144,6 +144,7 @@
 #define IPR_IOA_MAX_SECTORS                             32767
 #define IPR_VSET_MAX_SECTORS                            512
 #define IPR_MAX_CDB_LEN                                 16
+#define IPR_MAX_HRRQ_RETRIES                            3
 
 #define IPR_DEFAULT_BUS_WIDTH                           16
 #define IPR_80MBs_SCSI_RATE             ((80 * 10) / (IPR_DEFAULT_BUS_WIDTH / 8))