Input: elants_i2c - use DMA safe i2c when possible

To avoid bounce buffer when an i2c controller decides to use DMA for a
transaction, let's make out buffer that we use for reads DMA-safe and let
the master know that DMAing into it is safe.
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/elants_i2c.c

@@ -147,10 +147,11 @@ struct elants_data {
 	u8 cmd_resp[HEADER_SIZE];
 	struct completion cmd_done;
 
-	u8 buf[MAX_PACKET_SIZE];
-
 	bool wake_irq_enabled;
 	bool keep_power_in_suspend;
+
+	/* Must be last to be used for DMA operations */
+	u8 buf[MAX_PACKET_SIZE] ____cacheline_aligned;
 };
 
 static int elants_i2c_send(struct i2c_client *client,
@@ -863,7 +864,7 @@ static irqreturn_t elants_i2c_irq(int irq, void *_dev)
 	int i;
 	int len;
 
-	len = i2c_master_recv(client, ts->buf, sizeof(ts->buf));
+	len = i2c_master_recv_dmasafe(client, ts->buf, sizeof(ts->buf));
 	if (len < 0) {
 		dev_err(&client->dev, "%s: failed to read data: %d\n",
 			__func__, len);