3 files changed, 56 insertions, 11 deletions

diff --git a/Documentation/blockdev/cciss.txt b/Documentation/blockdev/cciss.txt
index c00c6a5ab21f..71464e09ec18 100644
--- a/Documentation/blockdev/cciss.txt
+++ b/Documentation/blockdev/cciss.txt
@@ -78,6 +78,16 @@ The device naming scheme is:
 /dev/cciss/c1d1p2               Controller 1, disk 1, partition 2
 /dev/cciss/c1d1p3               Controller 1, disk 1, partition 3
 
+CCISS simple mode support
+-------------------------
+
+The "cciss_simple_mode=1" boot parameter may be used to prevent the driver
+from putting the controller into "performant" mode. The difference is that
+with simple mode, each command completion requires an interrupt, while with
+"performant mode" (the default, and ordinarily better performing) it is
+possible to have multiple command completions indicated by a single
+interrupt.
+
 SCSI tape drive and medium changer support
 ------------------------------------------
 
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 8f4ef656a1af..61f0b5b6a415 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -68,6 +68,10 @@ static int cciss_tape_cmds = 6;
 module_param(cciss_tape_cmds, int, 0644);
 MODULE_PARM_DESC(cciss_tape_cmds,
         "number of commands to allocate for tape devices (default: 6)");
+static int cciss_simple_mode;
+module_param(cciss_simple_mode, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(cciss_simple_mode,
+        "Use 'simple mode' rather than 'performant mode'");
 
 static DEFINE_MUTEX(cciss_mutex);
 static struct proc_dir_entry *proc_cciss;
@@ -176,6 +180,7 @@ static void cciss_geometry_inquiry(ctlr_info_t *h, int logvol,
                         unsigned int block_size, InquiryData_struct *inq_buff,
                                    drive_info_struct *drv);
 static void __devinit cciss_interrupt_mode(ctlr_info_t *);
+static int __devinit cciss_enter_simple_mode(struct ctlr_info *h);
 static void start_io(ctlr_info_t *h);
 static int sendcmd_withirq(ctlr_info_t *h, __u8 cmd, void *buff, size_t size,
                         __u8 page_code, unsigned char scsi3addr[],
@@ -388,7 +393,7 @@ static void cciss_seq_show_header(struct seq_file *seq)
                 h->product_name,
                 (unsigned long)h->board_id,
                 h->firm_ver[0], h->firm_ver[1], h->firm_ver[2],
-                h->firm_ver[3], (unsigned int)h->intr[PERF_MODE_INT],
+                h->firm_ver[3], (unsigned int)h->intr[h->intr_mode],
                 h->num_luns,
                 h->Qdepth, h->commands_outstanding,
                 h->maxQsinceinit, h->max_outstanding, h->maxSG);
@@ -3984,6 +3989,9 @@ static void __devinit cciss_put_controller_into_performant_mode(ctlr_info_t *h)
 {
         __u32 trans_support;
 
+        if (cciss_simple_mode)
+                return;
+
         dev_dbg(&h->pdev->dev, "Trying to put board into Performant mode\n");
         /* Attempt to put controller into performant mode if supported */
         /* Does board support performant mode? */
@@ -4081,7 +4089,7 @@ static void __devinit cciss_interrupt_mode(ctlr_info_t *h)
 default_int_mode:
 #endif                          /* CONFIG_PCI_MSI */
         /* if we get here we're going to use the default interrupt mode */
-        h->intr[PERF_MODE_INT] = h->pdev->irq;
+        h->intr[h->intr_mode] = h->pdev->irq;
         return;
 }
 
@@ -4341,6 +4349,9 @@ static int __devinit cciss_pci_init(ctlr_info_t *h)
         }
         cciss_enable_scsi_prefetch(h);
         cciss_p600_dma_prefetch_quirk(h);
+        err = cciss_enter_simple_mode(h);
+        if (err)
+                goto err_out_free_res;
         cciss_put_controller_into_performant_mode(h);
         return 0;
 
@@ -4843,20 +4854,20 @@ static int cciss_request_irq(ctlr_info_t *h,
         irqreturn_t (*intxhandler)(int, void *))
 {
         if (h->msix_vector || h->msi_vector) {
-                if (!request_irq(h->intr[PERF_MODE_INT], msixhandler,
+                if (!request_irq(h->intr[h->intr_mode], msixhandler,
                                 IRQF_DISABLED, h->devname, h))
                         return 0;
                 dev_err(&h->pdev->dev, "Unable to get msi irq %d"
-                        " for %s\n", h->intr[PERF_MODE_INT],
+                        " for %s\n", h->intr[h->intr_mode],
                         h->devname);
                 return -1;
         }
 
-        if (!request_irq(h->intr[PERF_MODE_INT], intxhandler,
+        if (!request_irq(h->intr[h->intr_mode], intxhandler,
                         IRQF_DISABLED, h->devname, h))
                 return 0;
         dev_err(&h->pdev->dev, "Unable to get irq %d for %s\n",
-                h->intr[PERF_MODE_INT], h->devname);
+                h->intr[h->intr_mode], h->devname);
         return -1;
 }
 
@@ -4887,7 +4898,7 @@ static void cciss_undo_allocations_after_kdump_soft_reset(ctlr_info_t *h)
 {
         int ctlr = h->ctlr;
 
-        free_irq(h->intr[PERF_MODE_INT], h);
+        free_irq(h->intr[h->intr_mode], h);
 #ifdef CONFIG_PCI_MSI
         if (h->msix_vector)
                 pci_disable_msix(h->pdev);
@@ -4953,6 +4964,7 @@ reinit_after_soft_reset:
         h = hba[i];
         h->pdev = pdev;
         h->busy_initializing = 1;
+        h->intr_mode = cciss_simple_mode ? SIMPLE_MODE_INT : PERF_MODE_INT;
         INIT_LIST_HEAD(&h->cmpQ);
         INIT_LIST_HEAD(&h->reqQ);
         mutex_init(&h->busy_shutting_down);
@@ -5009,7 +5021,7 @@ reinit_after_soft_reset:
 
         dev_info(&h->pdev->dev, "%s: <0x%x> at PCI %s IRQ %d%s using DAC\n",
                h->devname, pdev->device, pci_name(pdev),
-               h->intr[PERF_MODE_INT], dac ? "" : " not");
+               h->intr[h->intr_mode], dac ? "" : " not");
 
         if (cciss_allocate_cmd_pool(h))
                 goto clean4;
@@ -5056,7 +5068,7 @@ reinit_after_soft_reset:
                 spin_lock_irqsave(&h->lock, flags);
                 h->access.set_intr_mask(h, CCISS_INTR_OFF);
                 spin_unlock_irqrestore(&h->lock, flags);
-                free_irq(h->intr[PERF_MODE_INT], h);
+                free_irq(h->intr[h->intr_mode], h);
                 rc = cciss_request_irq(h, cciss_msix_discard_completions,
                                         cciss_intx_discard_completions);
                 if (rc) {
@@ -5133,7 +5145,7 @@ clean4:
         cciss_free_cmd_pool(h);
         cciss_free_scatterlists(h);
         cciss_free_sg_chain_blocks(h->cmd_sg_list, h->nr_cmds);
-        free_irq(h->intr[PERF_MODE_INT], h);
+        free_irq(h->intr[h->intr_mode], h);
 clean2:
         unregister_blkdev(h->major, h->devname);
 clean1:
@@ -5172,9 +5184,31 @@ static void cciss_shutdown(struct pci_dev *pdev)
         if (return_code != IO_OK)
                 dev_warn(&h->pdev->dev, "Error flushing cache\n");
         h->access.set_intr_mask(h, CCISS_INTR_OFF);
-        free_irq(h->intr[PERF_MODE_INT], h);
+        free_irq(h->intr[h->intr_mode], h);