[PATCH v4 3/8] clk: add support for clocks provided by SCP(System Control Processor)

Sudeep Holla sudeep.holla at arm.com
Fri Jul 3 09:12:18 PDT 2015

On 03/07/15 15:52, Sudeep Holla wrote:


>>> +static int scpi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
>>> +			     unsigned long parent_rate)
>>> +{
>>> +	struct scpi_clk *clk = to_scpi_clk(hw);
>>> +
>>> +	return clk->scpi_ops->clk_set_val(clk->id, rate);
>>> +}
>>> +
>>> +static void scpi_clk_disable(struct clk_hw *hw)
>>> +{
>>> +	scpi_clk_set_rate(hw, 0, 0);
>> Does this mean you have to set a rate to enable the clock? Are
>> you relying on drivers to call clk_set_rate() to implicitly
>> enable the clock? If so, it would be better to cache the rate of
>> the clock in set_rate if the clock isn't enabled in software and
>> then send the cached rate during enable.
> Agreed, I have asked the firmware/SCPI specification guys about
> more details on what to expect from firmware. Once they get back,
> will update the code considering your feedback.

OK, I got feedback and looks like it was never planned to implement that
and even specification needs to be fixed. So I will drop the disable
callback support. For now, we don't support {en,dis}able
features. We need to amend the specification to fix that.


More information about the linux-arm-kernel mailing list