I2C_CLKDIV register descripted in the previous version of RK3x chip manual is incorrect. Plus 1 is required. The correct formula: - T(SCL_HIGH) = T(PCLK) * (CLKDIVH + 1) * 8 - T(SCL_LOW) = T(PCLK) * (CLKDIVL + 1) * 8 - (SCL Divsor) = 8 * ((CLKDIVL + 1) + (CLKDIVH + 1)) - SCL = PCLK / (CLK Divsor) It will be updated to the latest version of chip manual. Signed-off-by: Addy Ke <addy.ke@xxxxxxxxxxxxxx> --- drivers/i2c/busses/i2c-rk3x.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c index e637c32..76b6604 100644 --- a/drivers/i2c/busses/i2c-rk3x.c +++ b/drivers/i2c/busses/i2c-rk3x.c @@ -433,8 +433,8 @@ static void rk3x_i2c_set_scl_rate(struct rk3x_i2c *i2c, unsigned long scl_rate) unsigned long i2c_rate = clk_get_rate(i2c->clk); unsigned int div; - /* SCL rate = (clk rate) / (8 * DIV) */ - div = DIV_ROUND_UP(i2c_rate, scl_rate * 8); + /* SCL rate = (clk rate) / (8 * (DIV + 2)) */ + div = DIV_ROUND_UP(i2c_rate, scl_rate * 8) - 2; /* The lower and upper half of the CLKDIV reg describe the length of * SCL low & high periods. */ -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
