1 files changed, 13 insertions, 7 deletions

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 15eef94927e7..9325db49b4df 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -231,6 +231,7 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv,
         u32 round, ick;
         u32 scl;
         u32 cdf_width;
+        unsigned long rate;
 
         if (!clkp) {
                 dev_err(dev, "there is no peripheral_clk\n");
@@ -264,15 +265,14 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv,
          * clkp : peripheral_clk
          * F[]  : integer up-valuation
          */
-        for (cdf = 0; cdf < (1 << cdf_width); cdf++) {
-                ick = clk_get_rate(clkp) / (1 + cdf);
-                if (ick < 20000000)
-                        goto ick_find;
+        rate = clk_get_rate(clkp);
+        cdf = rate / 20000000;
+        if (cdf >= 1 << cdf_width) {
+                dev_err(dev, "Input clock %lu too high\n", rate);
+                return -EIO;
         }
-        dev_err(dev, "there is no best CDF\n");
-        return -EIO;
+        ick = rate / (cdf + 1);
 
-ick_find:
         /*
          * it is impossible to calculate large scale
          * number on u32. separate it
@@ -290,6 +290,12 @@ ick_find:
          *
          * Calculation result (= SCL) should be less than
          * bus_speed for hardware safety
+         *
+         * We could use something along the lines of
+         *      div = ick / (bus_speed + 1) + 1;
+         *      scgd = (div - 20 - round + 7) / 8;
+         *      scl = ick / (20 + (scgd * 8) + round);
+         * (not fully verified) but that would get pretty involved
          */
         for (scgd = 0; scgd < 0x40; scgd++) {
                 scl = ick / (20 + (scgd * 8) + round);