Merge remote-tracking branch 'spi/topic/core' into spi-next

drivers/spi/spi.c

@@ -552,6 +552,9 @@ int spi_register_board_info(struct spi_board_info const *info, unsigned n)
 	struct boardinfo *bi;
 	int i;
 
+	if (!n)
+		return -EINVAL;
+
 	bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
 	if (!bi)
 		return -ENOMEM;
@@ -789,27 +792,35 @@ static int spi_transfer_one_message(struct spi_master *master,
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 		trace_spi_transfer_start(msg, xfer);
 
-		reinit_completion(&master->xfer_completion);
+		if (xfer->tx_buf || xfer->rx_buf) {
+			reinit_completion(&master->xfer_completion);
 
-		ret = master->transfer_one(master, msg->spi, xfer);
-		if (ret < 0) {
-			dev_err(&msg->spi->dev,
-				"SPI transfer failed: %d\n", ret);
-			goto out;
-		}
+			ret = master->transfer_one(master, msg->spi, xfer);
+			if (ret < 0) {
+				dev_err(&msg->spi->dev,
+					"SPI transfer failed: %d\n", ret);
+				goto out;
+			}
 
-		if (ret > 0) {
-			ret = 0;
-			ms = xfer->len * 8 * 1000 / xfer->speed_hz;
-			ms += ms + 100; /* some tolerance */
+			if (ret > 0) {
+				ret = 0;
+				ms = xfer->len * 8 * 1000 / xfer->speed_hz;
+				ms += ms + 100; /* some tolerance */
 
-			ms = wait_for_completion_timeout(&master->xfer_completion,
-							 msecs_to_jiffies(ms));
-		}
+				ms = wait_for_completion_timeout(&master->xfer_completion,
+								 msecs_to_jiffies(ms));
+			}
 
-		if (ms == 0) {
-			dev_err(&msg->spi->dev, "SPI transfer timed out\n");
-			msg->status = -ETIMEDOUT;
+			if (ms == 0) {
+				dev_err(&msg->spi->dev,
+					"SPI transfer timed out\n");
+				msg->status = -ETIMEDOUT;
+			}
+		} else {
+			if (xfer->len)
+				dev_err(&msg->spi->dev,
+					"Bufferless transfer has length %u\n",
+					xfer->len);
 		}
 
 		trace_spi_transfer_stop(msg, xfer);