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;
@@ -789,6 +792,7 @@ 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);
 
+		if (xfer->tx_buf || xfer->rx_buf) {
 			reinit_completion(&master->xfer_completion);
 
 			ret = master->transfer_one(master, msg->spi, xfer);
@@ -808,9 +812,16 @@ static int spi_transfer_one_message(struct spi_master *master,
 			}
 
 			if (ms == 0) {
-			dev_err(&msg->spi->dev, "SPI transfer timed out\n");
+				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);