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SubjectRe: [PATCH] i2c-ocores: add common clock support
Date
>>>>> "Wolfram" == Wolfram Sang <wsa@the-dreams.de> writes:

>> @@ -320,9 +322,23 @@ static int ocores_i2c_of_probe(struct platform_device *pdev,
>> }
>>
>> if (of_property_read_u32(np, "clock-frequency", &val)) {
>> - dev_err(&pdev->dev,
>> - "Missing required parameter 'clock-frequency'\n");
>> - return -ENODEV;
>> + struct clk *clk = devm_clk_get(&pdev->dev, NULL);
>> +
>> + if (!IS_ERR(clk)) {
>> + int ret = clk_prepare_enable(clk);
>> +
>> + if (ret) {
>> + dev_err(&pdev->dev,
>> + "clk_prepare_enable failed: %d\n", ret);
>> + return ret;
>> + }
>> + i2c->clk = clk;
>> + val = clk_get_rate(clk);
>> + } else {
>> + dev_err(&pdev->dev,
>> + "Missing required parameter 'clock-frequency'\n");
>> + return -ENODEV;
>> + }

> Either NAK or I don't understand the logic here :) If a dts does NOT
> have the bus-speed set by 'clock-frequency', then we take the value of
> the clock assigned to this platform_device?

> The usual thing to do when 'clock-frequency' is not set is to default to
> 100kHz.

The confusion comes from the fact that the device tree bindings uses
clock-frequency for the clock frequency of the IP core and NOT for the
i2c bus frequency. This dates back to when the bindings where added
(049bb69d82e5f7f356) :/

The driver is currently hardcoded to use a 100KHz i2c bus clock (see
ocoores_init()).

--
Bye, Peter Korsgaard


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