Re: [PATCH 1/2] cpufreq: arm_big_little: check if the frequency is set correctly

[Sudeep Holla <sudeep.holla@arm.com>]

On 30/03/15 14:27, Viresh Kumar wrote:
> On 30 March 2015 at 17:57, Sudeep Holla <sudeep.holla@arm.com> wrote:
>> The actual frequency is set through "clk_change_rate" which is void
>> function. If the underlying hardware fails and returns error, the error
>> is lost in the clk layer. In order to track such failures, we need to
>> read back the frequency(just the cached value as clk_recalc called after
>> clk->ops->set_rate gets the frequency)
>>
>> This patch adds check to see if the frequency is set correctly or if
>> they were any hardware failures and sends the appropriate errors to the
>> cpufreq core.
>>
>> Cc: Viresh Kumar <viresh.kumar@linaro.org>
>> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
>> ---
>>   drivers/cpufreq/arm_big_little.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
>> index e1a6ba66a7f5..3fc676c63f91 100644
>> --- a/drivers/cpufreq/arm_big_little.c
>> +++ b/drivers/cpufreq/arm_big_little.c
>> @@ -186,6 +186,8 @@ bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate)
>>                  mutex_unlock(&cluster_lock[old_cluster]);
>>          }
>>
>> +       if (bL_cpufreq_get_rate(cpu) != new_rate)
>> +               return -EIO;
>>          return 0;
>>   }
>
> This doesn't look to me the right place for fixing this.
>

Yes I agree, after going through clk.c, I thought pre-/post- notifiers
are designed for such purpose. I tried using them but found it
unnecessary when it can be as simple as in this patch. However it's good
to hear from Mike as I seem to have assumed a lot here.

Regards,
Sudeep