Re: [PATCH v2 25/31] i2c: fsi: Calculate clock divider from local bus frequency

Eddie James
2024-04-16T18:09:27Z

On 4/15/24 17:11, Andi Shyti wrote:
> Hi Eddie,
>
>> @@ -689,6 +692,20 @@ static int fsi_i2c_probe(struct device *dev)
>> mutex_init(&i2c->lock);
>> i2c->fsi = to_fsi_dev(dev);
>> INIT_LIST_HEAD(&i2c->ports);
>> + i2c->clock_div = I2C_DEFAULT_CLK_DIV;
>> +
>> + lbus = fsi_device_local_bus_frequency(i2c->fsi);
>> + if (lbus) {
>> + u32 clock = I2C_DEFAULT_CLK_RATE;
> I don't see the need for initialization.

Does device_property_read_u32 set clock if the property isn't found? If
not, it needs to be initialized here. Or I can set it in an else
statement from device_property_read_u32.

>
>> +
>> + if (!device_property_read_u32(dev, "clock-frequency", &clock)) {
>> + if (!clock)
>> + clock = I2C_DEFAULT_CLK_RATE;
>> + }
> no need for brackets.

Perhaps not, but checkpatch didn't complain, and I personally like
brackets if multiple lines are included.

>
>> +
>> + // i2c clock rate = local bus clock / (4 * (i2c clock div + 1))
> You forgot to remove this.

I actually meant to leave that comment to explain how the clock rate is
calculated, as the reverse calculation in the code is a little more
confusing.

>
> Andi
>
>> + i2c->clock_div = (((lbus + (clock - 1)) / clock) / 4) - 1;
>> + }
>>
>> rc = fsi_i2c_dev_init(i2c);
>> if (rc)
>> --
>> 2.39.3
>>