i2c: rcar: skip DMA if buffer is not safe

This HW is prone to races, so it needs to setup new messages in irq
context. That means we can't alloc bounce buffers if a message buffer is
not DMA safe. So, in that case, simply fall back to PIO.
Reviewed-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-rcar.c

@@ -359,7 +359,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
 	int len;
 
 	/* Do not use DMA if it's not available or for messages < 8 bytes */
-	if (IS_ERR(chan) || msg->len < 8)
+	if (IS_ERR(chan) || msg->len < 8 || !(msg->flags & I2C_M_DMA_SAFE))
 		return;
 
 	if (read) {