hpilo: reduce frequency of IO operations

Change hpilo open and close logic to spin for 10usec between checking device,
rather than every usec.

Because the loop is coded to take up to 10ms, it seemed prudent to
increase the interval between polling the device, to reduce the load on
the system and allow more other work to happen.
Signed-off-by: NDavid Altobelli <david.altobelli@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/misc/hpilo.c

@@ -209,7 +209,7 @@ static void ilo_ccb_close(struct pci_dev *pdev, struct ccb_data *data)
 	/* give iLO some time to process stop request */
 	for (retries = MAX_WAIT; retries > 0; retries--) {
 		doorbell_set(driver_ccb);
-		udelay(1);
+		udelay(WAIT_TIME);
 		if (!(ioread32(&device_ccb->send_ctrl) & (1 << CTRL_BITPOS_A))
 		    &&
 		    !(ioread32(&device_ccb->recv_ctrl) & (1 << CTRL_BITPOS_A)))
@@ -312,7 +312,7 @@ static int ilo_ccb_open(struct ilo_hwinfo *hw, struct ccb_data *data, int slot)
 	for (i = MAX_WAIT; i > 0; i--) {
 		if (ilo_pkt_dequeue(hw, driver_ccb, SENDQ, &pkt_id, NULL, NULL))
 			break;
-		udelay(1);
+		udelay(WAIT_TIME);
 	}
 
 	if (i) {
@@ -759,7 +759,7 @@ static void __exit ilo_exit(void)
 	class_destroy(ilo_class);
 }
 
-MODULE_VERSION("1.0");
+MODULE_VERSION("1.1");
 MODULE_ALIAS(ILO_NAME);
 MODULE_DESCRIPTION(ILO_NAME);
 MODULE_AUTHOR("David Altobelli <david.altobelli@hp.com>");

drivers/misc/hpilo.h

@@ -19,8 +19,12 @@
 #define MAX_ILO_DEV	1
 /* max number of files */
 #define MAX_OPEN	(MAX_CCB * MAX_ILO_DEV)
+/* total wait time in usec */
+#define MAX_WAIT_TIME	10000
+/* per spin wait time in usec */
+#define WAIT_TIME	10
 /* spin counter for open/close delay */
-#define MAX_WAIT	10000
+#define MAX_WAIT	(MAX_WAIT_TIME / WAIT_TIME)
 
 /*
  * Per device, used to track global memory allocations.