i2c: imx: Only DMA messages with I2C_M_DMA_SAFE flag set

Recent changes to the DMA code has resulting in the IMX driver failing
I2C transfers when the buffer has been vmalloc. Only perform DMA
transfers if the message has the I2C_M_DMA_SAFE flag set, indicating
the client is providing a buffer which is DMA safe.

This is a minimal fix for stable. The I2C core provides helpers to
allocate a bounce buffer. For a fuller fix the master should make use
of these helpers.

Fixes: 4544b9f2 ("dma-mapping: Add vmap checks to dma_map_single()")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-imx.c

@@ -1132,7 +1132,8 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
 	int i, result;
 	unsigned int temp;
 	int block_data = msgs->flags & I2C_M_RECV_LEN;
-	int use_dma = i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data;
+	int use_dma = i2c_imx->dma && msgs->flags & I2C_M_DMA_SAFE &&
+		msgs->len >= DMA_THRESHOLD && !block_data;
 
 	dev_dbg(&i2c_imx->adapter.dev,
 		"<%s> write slave address: addr=0x%x\n",
@@ -1298,7 +1299,8 @@ static int i2c_imx_xfer_common(struct i2c_adapter *adapter,
 			result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg, atomic);
 		} else {
 			if (!atomic &&
-			    i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD)
+			    i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD &&
+				msgs[i].flags & I2C_M_DMA_SAFE)
 				result = i2c_imx_dma_write(i2c_imx, &msgs[i]);
 			else
 				result = i2c_imx_write(i2c_imx, &msgs[i], atomic);