1 files changed, 45 insertions, 19 deletions

diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c
index 4faf4f9ec06..59ad6e95af8 100644
--- a/drivers/w1/masters/ds2490.c
+++ b/drivers/w1/masters/ds2490.c
@@ -141,6 +141,10 @@ struct ds_device
 	 * 0: pullup not active, else duration in milliseconds
 	 */
 	int			spu_sleep;
+	/* spu_bit contains COMM_SPU or 0 depending on if the strong pullup
+	 * should be active or not for writes.
+	 */
+	u16			spu_bit;
 
 	struct w1_bus_master	master;
 };
@@ -311,6 +315,25 @@ static void ds_dump_status(struct ds_device *dev, unsigned char *buf, int count)
 	}
 }
 
+static void ds_reset_device(struct ds_device *dev)
+{
+	ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
+	/* Always allow strong pullup which allow individual writes to use
+	 * the strong pullup.
+	 */
+	if (ds_send_control_mode(dev, MOD_PULSE_EN, PULSE_SPUE))
+		printk(KERN_ERR "ds_reset_device: "
+			"Error allowing strong pullup\n");
+	/* Chip strong pullup time was cleared. */
+	if (dev->spu_sleep) {
+		/* lower 4 bits are 0, see ds_set_pullup */
+		u8 del = dev->spu_sleep>>4;
+		if (ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del))
+			printk(KERN_ERR "ds_reset_device: "
+				"Error setting duration\n");
+	}
+}
+
 static int ds_recv_data(struct ds_device *dev, unsigned char *buf, int size)
 {
 	int count, err;
@@ -444,7 +467,7 @@ static int ds_wait_status(struct ds_device *dev, struct ds_status *st)
 
 	if (err >= 16 && st->status & ST_EPOF) {
 		printk(KERN_INFO "Resetting device after ST_EPOF.\n");
-		ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
+		ds_reset_device(dev);
 		/* Always dump the device status. */
 		count = 101;
 	}
@@ -509,24 +532,26 @@ static int ds_set_speed(struct ds_device *dev, int speed)
 
 static int ds_set_pullup(struct ds_device *dev, int delay)
 {
-	int err;
+	int err = 0;
 	u8 del = 1 + (u8)(delay >> 4);
+	/* Just storing delay would not get the trunication and roundup. */
+	int ms = del<<4;
+
+	/* Enable spu_bit if a delay is set. */
+	dev->spu_bit = delay ? COMM_SPU : 0;
+	/* If delay is zero, it has already been disabled, if the time is
+	 * the same as the hardware was last programmed to, there is also
+	 * nothing more to do.  Compare with the recalculated value ms
+	 * rather than del or delay which can have a different value.
+	 */
+	if (delay == 0 || ms == dev->spu_sleep)
+		return err;
 
-	dev->spu_sleep = 0;
-	err = ds_send_control_mode(dev, MOD_PULSE_EN, delay ? PULSE_SPUE : 0);
+	err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del);
 	if (err)
 		return err;
 
-	if (delay) {
-		err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del);
-		if (err)
-			return err;
-
-		/* Just storing delay would not get the trunication and
-		 * roundup.
-		 */
-		dev->spu_sleep = del<<4;
-	}
+	dev->spu_sleep = ms;
 
 	return err;
 }
@@ -577,11 +602,11 @@ static int ds_write_byte(struct ds_device *dev, u8 byte)
 	struct ds_status st;
 	u8 rbyte;
 
-	err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM | COMM_SPU, byte);
+	err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM | dev->spu_bit, byte);
 	if (err)
 		return err;
 
-	if (dev->spu_sleep)
+	if (dev->spu_bit)
 		msleep(dev->spu_sleep);
 
 	err = ds_wait_status(dev, &st);
@@ -648,11 +673,11 @@ static int ds_write_block(struct ds_device *dev, u8 *buf, int len)
 	if (err < 0)
 		return err;
 
-	err = ds_send_control(dev, COMM_BLOCK_IO | COMM_IM | COMM_SPU, len);
+	err = ds_send_control(dev, COMM_BLOCK_IO | COMM_IM | dev->spu_bit, len);
 	if (err)
 		return err;
 
-	if (dev->spu_sleep)
+	if (dev->spu_bit)
 		msleep(dev->spu_sleep);
 
 	ds_wait_status(dev, &st);
@@ -849,7 +874,7 @@ static int ds_w1_init(struct ds_device *dev)
 	 * the input buffer.  This will cause the next read to fail
 	 * see the note in ds_recv_data.
 	 */
-	ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
+	ds_reset_device(dev);
 
 	dev->master.data	= dev;
 	dev->master.touch_bit	= &ds9490r_touch_bit;
@@ -892,6 +917,7 @@ static int ds_probe(struct usb_interface *intf,
 		return -ENOMEM;
 	}
 	dev->spu_sleep = 0;
+	dev->spu_bit = 0;
 	dev->udev = usb_get_dev(udev);
 	if (!dev->udev) {
 		err = -ENOMEM;