diff mbox

[v2] cpufreq: CPPC: Correct desired_perf calculation

Message ID 1476380015-21001-1-git-send-email-hotran@apm.com (mailing list archive)
State Accepted, archived
Delegated to: Rafael Wysocki
Headers show

Commit Message

hotran Oct. 13, 2016, 5:33 p.m. UTC
The desired_perf is an abstract performance number. Its value should
be in the range of [lowest perf, highest perf] of CPPC.
The correct calculation is
  desired_perf = freq * cppc_highest_perf / cppc_dmi_max_khz

And cppc_cpufreq_set_target() returns if desired_perf is exactly
the same with the old perf.

Signed-off-by: Hoan Tran <hotran@apm.com>
---
v2
 * Return if desired_perf is the same with the old one (Prashanth's suggestion)


 drivers/cpufreq/cppc_cpufreq.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Prakash, Prashanth Oct. 13, 2016, 7:37 p.m. UTC | #1
On 10/13/2016 11:33 AM, Hoan Tran wrote:
> The desired_perf is an abstract performance number. Its value should
> be in the range of [lowest perf, highest perf] of CPPC.
> The correct calculation is
>   desired_perf = freq * cppc_highest_perf / cppc_dmi_max_khz
>
> And cppc_cpufreq_set_target() returns if desired_perf is exactly
> the same with the old perf.
>
> Signed-off-by: Hoan Tran <hotran@apm.com>
Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org>

Hi Rafael,
Can you please pick this one for 4.9, as it is bug fix?

--
Thanks,
Prashanth
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Rafael J. Wysocki Oct. 13, 2016, 9:12 p.m. UTC | #2
On Thu, Oct 13, 2016 at 9:37 PM, Prakash, Prashanth
<pprakash@codeaurora.org> wrote:
> On 10/13/2016 11:33 AM, Hoan Tran wrote:
>> The desired_perf is an abstract performance number. Its value should
>> be in the range of [lowest perf, highest perf] of CPPC.
>> The correct calculation is
>>   desired_perf = freq * cppc_highest_perf / cppc_dmi_max_khz
>>
>> And cppc_cpufreq_set_target() returns if desired_perf is exactly
>> the same with the old perf.
>>
>> Signed-off-by: Hoan Tran <hotran@apm.com>
> Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org>
>
> Hi Rafael,
> Can you please pick this one for 4.9, as it is bug fix?

Sure, I will queue it up.

Thanks,
Rafael
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hotran Oct. 13, 2016, 9:21 p.m. UTC | #3
On Thu, Oct 13, 2016 at 2:12 PM, Rafael J. Wysocki <rafael@kernel.org> wrote:
> On Thu, Oct 13, 2016 at 9:37 PM, Prakash, Prashanth
> <pprakash@codeaurora.org> wrote:
>> On 10/13/2016 11:33 AM, Hoan Tran wrote:
>>> The desired_perf is an abstract performance number. Its value should
>>> be in the range of [lowest perf, highest perf] of CPPC.
>>> The correct calculation is
>>>   desired_perf = freq * cppc_highest_perf / cppc_dmi_max_khz
>>>
>>> And cppc_cpufreq_set_target() returns if desired_perf is exactly
>>> the same with the old perf.
>>>
>>> Signed-off-by: Hoan Tran <hotran@apm.com>
>> Reviewed-by: Prashanth Prakash <pprakash@codeaurora.org>
>>
>> Hi Rafael,
>> Can you please pick this one for 4.9, as it is bug fix?
>
> Sure, I will queue it up.
>

Thanks, Rafael and Prashanth !

Hoan

> Thanks,
> Rafael
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diff mbox

Patch

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 1b2f28f..4852d9e 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -80,11 +80,17 @@  static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
 {
 	struct cppc_cpudata *cpu;
 	struct cpufreq_freqs freqs;
+	u32 desired_perf;
 	int ret = 0;
 
 	cpu = all_cpu_data[policy->cpu];
 
-	cpu->perf_ctrls.desired_perf = (u64)target_freq * policy->max / cppc_dmi_max_khz;
+	desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
+	/* Return if it is exactly the same perf */
+	if (desired_perf == cpu->perf_ctrls.desired_perf)
+		return ret;
+
+	cpu->perf_ctrls.desired_perf = desired_perf;
 	freqs.old = policy->cur;
 	freqs.new = target_freq;