[SCSI] mpt2sas: Set max_sector count from module parameter
This feature is to override the default
max_sectors setting at load time, taking max_sectors as an
command line option when loading the driver. The setting is
currently hard-coded in the driver to 8192 sectors (4MB transfers).
If max_sectors is specified at load time, minimum specified
setting will be 64, and the maximum is 8192. The driver will
modify the setting to be on even boundary. If max_sectors is not
specified, the driver will default to 8192.
Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/mpt2sas/mpt2sas_scsih.c b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
index e327a3c..f86f2b1 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_scsih.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_scsih.c
@@ -94,6 +94,10 @@
MODULE_PARM_DESC(logging_level, " bits for enabling additional logging info "
"(default=0)");
+static ushort max_sectors = 0xFFFF;
+module_param(max_sectors, ushort, 0);
+MODULE_PARM_DESC(max_sectors, "max sectors, range 64 to 8192 default=8192");
+
/* scsi-mid layer global parmeter is max_report_luns, which is 511 */
#define MPT2SAS_MAX_LUN (16895)
static int max_lun = MPT2SAS_MAX_LUN;
@@ -7436,6 +7440,25 @@
shost->transportt = mpt2sas_transport_template;
shost->unique_id = ioc->id;
+ if (max_sectors != 0xFFFF) {
+ if (max_sectors < 64) {
+ shost->max_sectors = 64;
+ printk(MPT2SAS_WARN_FMT "Invalid value %d passed "
+ "for max_sectors, range is 64 to 8192. Assigning "
+ "value of 64.\n", ioc->name, max_sectors);
+ } else if (max_sectors > 8192) {
+ shost->max_sectors = 8192;
+ printk(MPT2SAS_WARN_FMT "Invalid value %d passed "
+ "for max_sectors, range is 64 to 8192. Assigning "
+ "default value of 8192.\n", ioc->name,
+ max_sectors);
+ } else {
+ shost->max_sectors = max_sectors & 0xFFFE;
+ printk(MPT2SAS_INFO_FMT "The max_sectors value is "
+ "set to %d\n", ioc->name, shost->max_sectors);
+ }
+ }
+
if ((scsi_add_host(shost, &pdev->dev))) {
printk(MPT2SAS_ERR_FMT "failure at %s:%d/%s()!\n",
ioc->name, __FILE__, __LINE__, __func__);