[SCSI] megaraid_sas: Add input parameter for max_sectors

Driver add the input parameters support for max_sectors for megaraid
sas gen2 chip.  Customer can set the max_sectors support to 1MB for
gen2 chip during the driver load.

Signed-off-by Bo Yang <bo.yang@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

2 files changed, 31 insertions, 0 deletions

diff --git a/drivers/scsi/megaraid/megaraid_sas.c b/drivers/scsi/megaraid/megaraid_sas.c
index 09a455d4b6ed..41ffc205724f 100644
--- a/drivers/scsi/megaraid/megaraid_sas.c
+++ b/drivers/scsi/megaraid/megaraid_sas.c
@@ -56,6 +56,15 @@ module_param_named(poll_mode_io, poll_mode_io, int, 0);
 MODULE_PARM_DESC(poll_mode_io,
         "Complete cmds from IO path, (default=0)");
 
+/*
+ * Number of sectors per IO command
+ * Will be set in megasas_init_mfi if user does not provide
+ */
+static unsigned int max_sectors;
+module_param_named(max_sectors, max_sectors, int, 0);
+MODULE_PARM_DESC(max_sectors,
+        "Maximum number of sectors per IO command");
+
 MODULE_LICENSE("GPL");
 MODULE_VERSION(MEGASAS_VERSION);
 MODULE_AUTHOR("megaraidlinux@lsi.com");
@@ -3586,6 +3595,27 @@ static int megasas_io_attach(struct megasas_instance *instance)
                         instance->max_fw_cmds - MEGASAS_INT_CMDS;
         host->this_id = instance->init_id;
         host->sg_tablesize = instance->max_num_sge;
+        /*
+         * Check if the module parameter value for max_sectors can be used
+         */
+        if (max_sectors && max_sectors < instance->max_sectors_per_req)
+                instance->max_sectors_per_req = max_sectors;
+        else {
+                if (max_sectors) {
+                        if (((instance->pdev->device ==
+                                PCI_DEVICE_ID_LSI_SAS1078GEN2) ||
+                                (instance->pdev->device ==
+                                PCI_DEVICE_ID_LSI_SAS0079GEN2)) &&
+                                (max_sectors <= MEGASAS_MAX_SECTORS)) {
+                                instance->max_sectors_per_req = max_sectors;
+                        } else {
+                        printk(KERN_INFO "megasas: max_sectors should be > 0"
+                                "and <= %d (or < 1MB for GEN2 controller)\n",
+                                instance->max_sectors_per_req);
+                        }
+                }
+        }
+
         host->max_sectors = instance->max_sectors_per_req;
         host->cmd_per_lun = 128;
         host->max_channel = MEGASAS_MAX_CHANNELS - 1;
diff --git a/drivers/scsi/megaraid/megaraid_sas.h b/drivers/scsi/megaraid/megaraid_sas.h
index 16a4f68a34b0..54d1a154b448 100644
--- a/drivers/scsi/megaraid/megaraid_sas.h
+++ b/drivers/scsi/megaraid/megaraid_sas.h
@@ -706,6 +706,7 @@ struct megasas_ctrl_info {
 #define MEGASAS_MAX_LD_IDS                      (MEGASAS_MAX_LD_CHANNELS * \
                                                 MEGASAS_MAX_DEV_PER_CHANNEL)
 
+#define MEGASAS_MAX_SECTORS                    (2*1024)
 #define MEGASAS_DBG_LVL                         1
 
 #define MEGASAS_FW_BUSY                         1