i2c-designware: Initialize byte count variables just prior to being used

As the driver and hardware always process the given data in parallel,
then it would be better to initialize tx_limit, rx_limit and rx_valid
variables just prior to being used.

This will help us to send / receive as much data as possible.
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

drivers/i2c/busses/i2c-designware.c

@@ -360,8 +360,7 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
 {
 	struct i2c_msg *msgs = dev->msgs;
 	u32 intr_mask;
-	int tx_limit = dev->tx_fifo_depth - readl(dev->base + DW_IC_TXFLR);
-	int rx_limit = dev->rx_fifo_depth - readl(dev->base + DW_IC_RXFLR);
+	int tx_limit, rx_limit;
 	u32 addr = msgs[dev->msg_write_idx].addr;
 	u32 buf_len = dev->tx_buf_len;
 	u8 *buf = dev->tx_buf;;
@@ -389,6 +388,9 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
 			buf_len = msgs[dev->msg_write_idx].len;
 		}
 
+		tx_limit = dev->tx_fifo_depth - readl(dev->base + DW_IC_TXFLR);
+		rx_limit = dev->rx_fifo_depth - readl(dev->base + DW_IC_RXFLR);
+
 		while (buf_len > 0 && tx_limit > 0 && rx_limit > 0) {
 			if (msgs[dev->msg_write_idx].flags & I2C_M_RD) {
 				writel(0x100, dev->base + DW_IC_DATA_CMD);
@@ -418,7 +420,7 @@ i2c_dw_read(struct dw_i2c_dev *dev)
 {
 	struct i2c_msg *msgs = dev->msgs;
 	u32 addr = msgs[dev->msg_read_idx].addr;
-	int rx_valid = readl(dev->base + DW_IC_RXFLR);
+	int rx_valid;
 
 	for (; dev->msg_read_idx < dev->msgs_num; dev->msg_read_idx++) {
 		u32 len;
@@ -439,6 +441,8 @@ i2c_dw_read(struct dw_i2c_dev *dev)
 			buf = dev->rx_buf;
 		}
 
+		rx_valid = readl(dev->base + DW_IC_RXFLR);
+
 		for (; len > 0 && rx_valid > 0; len--, rx_valid--)
 			*buf++ = readl(dev->base + DW_IC_DATA_CMD);