On 4/6/20 10:17 PM, Daniel Lezcano wrote:
On 06/04/2020 18:07, Lukasz Luba wrote:
On 4/6/20 3:58 PM, Daniel Lezcano wrote:
Hi Lukasz,
On 06/04/2020 15:29, Lukasz Luba wrote:
Hi Daniel,
Thank you for the review.
On 4/3/20 5:05 PM, Daniel Lezcano wrote:
Hi Lukasz,
On 18/03/2020 12:45, Lukasz Luba wrote:
Add support of other devices into the Energy Model framework not only
the
CPUs. Change the interface to be more unified which can handle other
devices as well.
thanks for taking care of that. Overall I like the changes in this
patch
but it hard to review in details because the patch is too big :/
Could you split this patch into smaller ones?
eg. (at your convenience)
- One patch renaming s/cap/perf/
- One patch adding a new function:
em_dev_register_perf_domain(struct device *dev,
unsigned int nr_states,
struct em_data_callback *cb);
(+ EXPORT_SYMBOL_GPL)
And em_register_perf_domain() using it.
- One converting the em_register_perf_domain() user to
em_dev_register_perf_domain
- One adding the different new 'em' functions
- And finally one removing em_register_perf_domain().
I agree and will do the split. I could also break the dependencies
for future easier merge.
Acked-by: Quentin Perret <qperret@xxxxxxxxxx>
Signed-off-by: Lukasz Luba <lukasz.luba@xxxxxxx>
---
[ ... ]
2. Core APIs
@@ -70,14 +72,16 @@ CONFIG_ENERGY_MODEL must be enabled to use the EM
framework.
Drivers are expected to register performance domains into the EM
framework by
calling the following API::
- int em_register_perf_domain(cpumask_t *span, unsigned int
nr_states,
- struct em_data_callback *cb);
+ int em_register_perf_domain(struct device *dev, unsigned int
nr_states,
+ struct em_data_callback *cb, cpumask_t *cpus);
Isn't possible to get rid of this cpumask by using
cpufreq_cpu_get() which returns the cpufreq's policy and from their get
the related cpus ?
We had similar thoughts with Quentin and I've checked this.
Yeah, I suspected you already think about that :)
Unfortunately, if the policy is a 'new policy' [1] it gets
allocated and passed into cpufreq driver ->init(policy) [2].
Then that policy is set into per_cpu pointer for each related_cpu [3]:
for_each_cpu(j, policy->related_cpus)
per_cpu(cpufreq_cpu_data, j) = policy;
Thus, any calls of functions (i.e. cpufreq_cpu_get()) which try to
take this ptr before [3] won't work.
We are trying to register EM from cpufreq_driver->init(policy) and the
per_cpu policy is likely to be not populated at that phase.
What is the problem of registering at the end of the cpufreq_online ?
We want to enable driver developers to choose one of two options for the
registration of Energy Model:
1. a simple one via dev_pm_opp_of_register_em(), which uses default
callback function calculating power based on: voltage, freq
and DT entry 'dynamic-power-coefficient' for each OPP
2. a more sophisticated, when driver provides callback function, which
will be called from EM for each OPP to ask for related power;
This interface could also be used by devices which relay not only
on one source of 'voltage', i.e. manipulate body bias or have
other controlling voltage for gates in the new 3D transistors. They
might provide custom callback function in their cpufreq driver.
This is used i.e. in cpufreq drivers which use firmware to get power,
like scmi-cpufreq.c;
To meet this requirement the registration of EM is moved into cpufreq
drivers, not in the framework i.e cpufreq_online(). If we could limit
the support for only option 1. then we could move the registration
call into cpufreq framework and clean the cpufreq drivers.
I'm not sure to get your point but I think a series setting the scene by
moving the dev_pm_opp_of_register_em() to cpufreq_online() and remove
the cpumask may make sense.
Some of the cpufreq drivers don't use dev_pm_opp_of_register_em() but
instead em_register_perf_domain() with their em_data_callback [1].
It is because of point 2. described above. The dev_pm_opp_of_register_em
won't work for them, so it's not a good candidate to cover all use cases
in the framework.
Can you send the split version of patch 1/5 as a series without the
other changes ? So we can focus on first ?
Sure, I will only split patch 1/5 as you suggested and send v6.
Thank you for your time and help.
Regards,
Lukasz
[1]
https://elixir.bootlin.com/linux/latest/source/drivers/cpufreq/scmi-cpufreq.c#L203
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