mfd: Remove copy from WM831x I2C write function

This saves us allocating an array on the stack, giving a meaningless
performance improvement and ensuring that if drivers ever do large writes
we'll not allocate large arrays on the stack.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 13 insertions, 5 deletions

diff --git a/drivers/mfd/wm831x-i2c.c b/drivers/mfd/wm831x-i2c.c
index 3853fa8e7cc2..a06cbc739716 100644
--- a/drivers/mfd/wm831x-i2c.c
+++ b/drivers/mfd/wm831x-i2c.c
@@ -51,17 +51,25 @@ static int wm831x_i2c_write_device(struct wm831x *wm831x, unsigned short reg,
                                    int bytes, void *src)
 {
         struct i2c_client *i2c = wm831x->control_data;
-        unsigned char msg[bytes + 2];
+        struct i2c_msg xfer[2];
         int ret;
 
         reg = cpu_to_be16(reg);
-        memcpy(&msg[0], &reg, 2);
-        memcpy(&msg[2], src, bytes);
 
-        ret = i2c_master_send(i2c, msg, bytes + 2);
+        xfer[0].addr = i2c->addr;
+        xfer[0].flags = 0;
+        xfer[0].len = 2;
+        xfer[0].buf = (char *)®
+
+        xfer[1].addr = i2c->addr;
+        xfer[1].flags = I2C_M_NOSTART;
+        xfer[1].len = bytes;
+        xfer[1].buf = (char *)src;
+
+        ret = i2c_transfer(i2c->adapter, xfer, 2);
         if (ret < 0)
                 return ret;
-        if (ret < bytes + 2)
+        if (ret != 2)
                 return -EIO;
 
         return 0;