1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c
index 9a7fd71e1461..0f356939b349 100644
--- a/drivers/w1/masters/ds2490.c
+++ b/drivers/w1/masters/ds2490.c
@@ -316,6 +316,15 @@ static int ds_recv_data(struct ds_device *dev, unsigned char *buf, int size)
         int count, err;
         struct ds_status st;
 
+        /* Careful on size.  If size is less than what is available in
+         * the input buffer, the device fails the bulk transfer and
+         * clears the input buffer.  It could read the maximum size of
+         * the data buffer, but then do you return the first, last, or
+         * some set of the middle size bytes?  As long as the rest of
+         * the code is correct there will be size bytes waiting.  A
+         * call to ds_wait_status will wait until the device is idle
+         * and any data to be received would have been available.
+         */
         count = 0;
         err = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]),
                                 buf, size, &count, 1000);
@@ -824,6 +833,18 @@ static int ds_w1_init(struct ds_device *dev)
 {
         memset(&dev->master, 0, sizeof(struct w1_bus_master));
 
+        /* Reset the device as it can be in a bad state.
+         * This is necessary because a block write will wait for data
+         * to be placed in the output buffer and block any later
+         * commands which will keep accumulating and the device will
+         * not be idle.  Another case is removing the ds2490 module
+         * while a bus search is in progress, somehow a few commands
+         * get through, but the input transfers fail leaving data in
+         * 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);
+
         dev->master.data        = dev;
         dev->master.touch_bit   = &ds9490r_touch_bit;
         /* read_bit and write_bit in w1_bus_master are expected to set and