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Subject[PATCH 5/7] scsi: megaraid_sas - Add input parameter for max_sectors
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@lsi.com>

---
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 2010-05-03 05:50:40.000000000 -0400
+++ new/drivers/scsi/megaraid/megaraid_sas.c 2010-05-03 09:55:58.000000000 -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 = 0;
+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");
@@ -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 2010-05-03 05:50:40.000000000 -0400
+++ new/drivers/scsi/megaraid/megaraid_sas.h 2010-05-03 09:56:08.000000000 -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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