Hi Maxime,
>>> +static void stm32f4_i2c_set_speed_mode(struct stm32f4_i2c_dev *i2c_dev)
>>> +{
>>> + struct stm32f4_i2c_timings *t = &i2c_timings[i2c_dev->speed];
>>> + u32 ccr, val, clk_rate;
>>> +
>>> + ccr = readl_relaxed(i2c_dev->base + STM32F4_I2C_CCR);
>>> + ccr &= ~(STM32F4_I2C_CCR_FS | STM32F4_I2C_CCR_DUTY |
>>> + STM32F4_I2C_CCR_CCR_MASK);
>>> +
>>> + clk_rate = clk_get_rate(i2c_dev->clk);
>>> +
>>> + switch (i2c_dev->speed) {
>>> + case STM32F4_I2C_SPEED_STANDARD:
>>> + val = clk_rate / t->rate * 2;
>>> + if (val < STM32F4_I2C_MIN_CCR)
>>> + ccr |= STM32F4_I2C_CCR_CCR(STM32F4_I2C_MIN_CCR);
>>> + else
>>> + ccr |= STM32F4_I2C_CCR_CCR(val);
>>> + break;
>>> + case STM32F4_I2C_SPEED_FAST:
>>> + ccr |= STM32F4_I2C_CCR_FS;
>>> + if (t->duty) {
>>> + ccr |= STM32F4_I2C_CCR_DUTY;
>>> + ccr |= STM32F4_I2C_CCR_CCR(clk_rate / t->rate * 25);
>>> + } else {
>>> + ccr |= STM32F4_I2C_CCR_CCR(clk_rate / t->rate * 3);
>>> + }
>> Is it really useful since duty seems to always be 0?
> Agree, I will rework it by directly set duty at 0 in the register.
Contrary to what I wrote previously, the duty has to be set for FAST
Mode to reach 400khz.
So, I am going to keep the timing struct and set duty to 1 for FAST mode
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