[PATCH V4 38/62] SPEAr CPU freq: Adding support for CPU Freq framework

[viresh kumar]

On Wed, Jan 19, 2011 at 3:23 PM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Wed, Jan 19, 2011 at 03:09:42PM +0530, Shiraz Hashim wrote:
>> On second thought it should always be there irrespective of failures
>> as in our case it may happen that eventually CPU sets to a clock <=
>> desired clock. So we would do following
>>
>> cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
>> ret = clk_set_rate(cpu_clk, freqs.new * 1000);
>> if (ret)
>>         pr_err("Could not change cpu clk rate\n");
>> freqs.new = clk_get_rate(cpu_clk);
>> cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
>
> It probably makes more sense to do:
>
>        newfreq = clk_round_rate(cpu_clk, freqs.new * 1000);
>        if (newfreq < 0) {
>                pr_err("Invalid frequency blah blah\n");
>                return newfreq;
>        }
>
>        freqs.new = newfreq / 1000;
>        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
>        ret = clk_set_rate(cpu_clk, newfreq);
>        if (ret) {
>                pr_err("Could not change cpu clk rate\n");
>                freqs.new = clk_get_rate(cpu_clk) / 1000;
>        }
>        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
>
> so that the prechange notifier gets the actual frequency to be switched
> to too.  In theory clk_set_rate() should only fail if the new frequency
> couldn't be set for some reason.
>

Ok.