[PATCH 10/12] scsi: megaraid_sas - Add input parameter formax_sectors

[Yang, Bo]

Driver add the input parameters support for max_sectors for our 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@xxxxxxx>

---
megaraid_sas.c |   74 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
megaraid_sas.h |    1
 2 files changed, 75 insertions(+)

diff -rupN old/drivers/scsi/megaraid/megaraid_sas.c new/drivers/scsi/megaraid/megaraid_sas.c
--- old/drivers/scsi/megaraid/megaraid_sas.c	2010-06-08 09:04:38.000000000 -0400
+++ new/drivers/scsi/megaraid/megaraid_sas.c	2010-06-08 09:51:56.000000000 -0400
@@ -57,6 +57,15 @@ module_param_named(poll_mode_io, poll_mo
 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@xxxxxxx");
@@ -3566,6 +3575,32 @@ static int megasas_start_aen(struct mega
 				    class_locale.word);
 }
 
+static ssize_t
+sysfs_max_sectors_read(struct kobject *kobj, struct bin_attribute *bin_attr,
+			char *buf, loff_t off, size_t count)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+
+	struct Scsi_Host *host = class_to_shost(dev);
+
+	struct megasas_instance *instance =
+				(struct megasas_instance *)host->hostdata;
+
+	count = sprintf(buf, "%u\n", instance->max_sectors_per_req);
+
+	return count+1;
+}
+
+static struct bin_attribute sysfs_max_sectors_attr = {
+	.attr = {
+		.name = "max_sectors",
+		.mode = S_IRUSR|S_IRGRP|S_IROTH,
+		.owner = THIS_MODULE,
+	},
+	.size = 7,
+	.read = sysfs_max_sectors_read,
+};
+
 /**
  * megasas_io_attach -	Attaches this driver to SCSI mid-layer
  * @instance:		Adapter soft state
@@ -3573,6 +3608,7 @@ static int megasas_start_aen(struct mega
 static int megasas_io_attach(struct megasas_instance *instance)
 {
 	struct Scsi_Host *host = instance->host;
+	u32		error;
 
 	/*
 	 * Export parameters required by SCSI mid-layer
@@ -3588,6 +3624,27 @@ static int megasas_io_attach(struct mega
 			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;
@@ -3604,10 +3661,27 @@ static int megasas_io_attach(struct mega
 	}
 
 	/*
+	 * Create sysfs entries for module paramaters
+	 */
+	error = sysfs_create_bin_file(&instance->host->shost_dev.kobj,
+			&sysfs_max_sectors_attr);
+
+	if (error) {
+		printk(KERN_INFO "megasas: Error in creating the sysfs entry"
+				" max_sectors.\n");
+		goto out_remove_host;
+	}
+
+	/*
 	 * Trigger SCSI to scan our drives
 	 */
 	scsi_scan_host(host);
 	return 0;
+
+out_remove_host:
+	scsi_remove_host(host);
+	return error;
+
 }
 
 static int
diff -rupN old/drivers/scsi/megaraid/megaraid_sas.h new/drivers/scsi/megaraid/megaraid_sas.h
--- old/drivers/scsi/megaraid/megaraid_sas.h	2010-06-08 09:04:38.000000000 -0400
+++ new/drivers/scsi/megaraid/megaraid_sas.h	2010-06-08 09:04:38.000000000 -0400
@@ -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
--
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