[PATCH v2 0/8] PM / devfreq: Use OPP interface to handle the frequency

[Chanwoo Choi]

These patches makes the devfreq to use the OPP interface and clean-up codes.
- patch 1~5 are related to the OPP interfaces. 
- patch 6 removes the unneeded code.
- patch 7 clean-up for the governor name.
- patch 8 registers the cooling device for exynos-bus.

[Detaild Descripion]
The commit a76caf55e5b3 ("thermal: Add devfreq cooling") provides
the devfreq cooling device by using the OPP interface such as
dev_pm_opp_disable() and dev_pm_opp_enable(). It means that
the OPP interface is able to change the available status of the frequency.

Firstly, the existing devfreq doesn't use the OPP interface when showing
the minimum and maximum frequency through the following sysfs nodes:
It shows the wrong frequency value because min_freq/max_freq don't
consider the frequency status by handling OPP interface
(opp_dev_pm_opp_{disable|add}()). So, these patches fix this issue.
- /sys/class/devfreq/devfreqX/min_freq
- /sys/class/devfreq/devfreqX/max_freq

Second, the 'available_frequencies' should show the all supported frequencis
even if the specific frequency is not available. It doesn't matter whether
frequneyc is available or not. Because the role of 'available_frequencies'
shows the all frequencies. Also, these patches fix this issue.
- /sys/class/devfreq/devfreqX/available_frequencies

Third, update_devfreq() get the available next frequency by using
the devfreq_recommended_opp() in order to consider the disabled OPP.

For example,
- devfreq's min_freq is 100Mhz and max_freq is 700Mhz.
- OPP disabled 500/600/700Mhz due to devfreq-cooling.c.
- simple_ondemand govenor decided the next target_freq (600Mhz)
|----------|-------------------------------------------------------------|
|Freq(MHz) |100     |200    |300    |400     |500     |600      |70 0    |
|Devfreq   |min_freq|       |       |        |        |         |max_freq|
|OPP avail |enabled |enabled|enabled|enabled |Disabled| Disabled|Disabled|
|Ondmenad  |        |       |       |        |        |next_freq|        |
|------------------------------------------------------------------------|

In result,
- Before this patch, target_freq is 600Mhz
  and TRANSITION_NOTIFIER sends the next_freq is 600Mhz to the notifiee.
- After this patch, target_freq is 400Mhz because 500/600 were disabled by OPP.
  And TRANSITION_NOTIFIER sends the next_freq is 400Mhz to the notifiee.

Lastly,
- patch6/7 fix the minor issue and cleanup codes.
- patch8 register the cooling device. It depends on opp patch[1].
[1] https://patchwork.kernel.org/patch/9962387/

Changes from v1:
(https://lkml.org/lkml/2017/8/23/785)
- Show the available frequencies as an ascending order
- Change the author info from cwchoi00@xxxxxxxxx to cw00.choi@xxxxxxxxxxx
- Drop the patches related to opp_notifier
- Add new patch5/6/7/8

Chanwoo Choi (8):
  PM / devfreq: Set min/max_freq when adding the devfreq device
  Revert "PM / devfreq: Add show_one macro to delete the duplicate code"
  PM / devfreq: Show the available min/max frequency through sysfs node
  PM / devfreq: Show the all available frequencies
  PM / devfreq: Get the available next frequency on update_devfreq()
  PM / devfreq: Remove unneeded conditional statement
  PM / devfreq: Define the constant governor name
  PM / devfreq: exynos-bus: Register cooling device

 drivers/devfreq/Kconfig                   |   1 +
 drivers/devfreq/devfreq.c                 | 121 +++++++++++++++++++++++-------
 drivers/devfreq/exynos-bus.c              |  16 +++-
 drivers/devfreq/governor_passive.c        |   2 +-
 drivers/devfreq/governor_performance.c    |   2 +-
 drivers/devfreq/governor_powersave.c      |   2 +-
 drivers/devfreq/governor_simpleondemand.c |   2 +-
 drivers/devfreq/governor_userspace.c      |   2 +-
 drivers/devfreq/rk3399_dmc.c              |   2 +-
 include/linux/devfreq.h                   |   7 ++
 10 files changed, 123 insertions(+), 34 deletions(-)

-- 
1.9.1