ENGR00236240 i2c: i2c performance optimization

It is unnecessary to calculate and update i2c divider during
every transaction. Only do it if current i2c clock is different
with the previous clock frequency.

Signed-off-by: Fugang Duan  <B38611@freescale.com>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 70b97b0e290ca9cf6c1d6d187e2426e57e9d410b..8cec1965dec3bf0b235cb6f7965cc905e26db73b 100644 (file)
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -96,7 +96,7 @@
  * Duplicated divider values removed from list
  */
 
-static u16 __initdata i2c_clk_div[50][2] = {
+static u16 i2c_clk_div[50][2] = {
        { 22,   0x20 }, { 24,   0x21 }, { 26,   0x22 }, { 28,   0x23 },
        { 30,   0x00 }, { 32,   0x24 }, { 36,   0x25 }, { 40,   0x26 },
        { 42,   0x03 }, { 44,   0x27 }, { 48,   0x28 }, { 52,   0x05 },
@@ -123,6 +123,7 @@ struct imx_i2c_struct {
        unsigned int            disable_delay;
        int                     stopped;
        unsigned int            ifdr; /* IMX_I2C_IFDR */
+       unsigned int            cur_clk;
 };
 
 /** Functions for IMX I2C adapter driver ***************************************
@@ -190,6 +191,10 @@ static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
 
        /* Divider value calculation */
        i2c_clk_rate = clk_get_rate(i2c_imx->clk);
+       if (i2c_imx->cur_clk == i2c_clk_rate)
+               return;
+       else
+               i2c_imx->cur_clk = i2c_clk_rate;
        div = (i2c_clk_rate + rate - 1) / rate;
        if (div < i2c_clk_div[0][0])
                i = 0;