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mfd: Remove copy from WM831x I2C write function

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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>
This commit is contained in:
Mark Brown
2011-03-17 21:40:51 +00:00
committed by Samuel Ortiz
parent aad343107b
commit 4c4d887822
1 changed files with 13 additions and 5 deletions
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18
drivers/mfd/wm831x-i2c.c
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@@ -51,17 +51,25 @@ static int wm831x_i2c_write_device(struct wm831x *wm831x, unsigned short reg,
int bytes, void *src) int bytes, void *src)
{ {
struct i2c_client *i2c = wm831x->control_data; struct i2c_client *i2c = wm831x->control_data;
unsigned char msg[bytes + 2]; struct i2c_msg xfer[2];
int ret; int ret;
reg = cpu_to_be16(reg); 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 *)&reg;
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) if (ret < 0)
return ret; return ret;
if (ret < bytes + 2) if (ret != 2)
return -EIO; return -EIO;
return 0; return 0;