[v2,00/11] thermal: add new flag irq-mode for trip point
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Lukasz Luba Nov. 7, 2018, 5:09 p.m. UTC
Hi all,

This patch set adds a new flag and mechanism in thermal trip points in
DT.  The old implementation in thermal zone in DT sets the same
configuration for all internal trip points. It does not work for all
HW.  There are SoCs which support IRQs for some trip points (i.e.
Exynos 4 has 4 trip points with IRQs). For additional one defined
inside the thermal zone there is a need of 'polling'. When developer
adds polling mode settings inside the thermal zone, all the trip
points will be registered for polling, even those supporting IRQs,
which does not make sense. Thus, developers create workarounds, which
are confusing for some other developers.  To workaround, 
people declare some trip points as 'active' (those with IRQ support).
It allows to bypass polling mode in thermal framework applied for 
all thermal zone's trip points.

Thermal framework defines 4 types of trip points. The 'passive' means
passive cooling using DVFS, 'active' is designed for fan and other
devices actively changing the outside conditions. Therefore, a workaround
mentioned earlier is confusing when someone does not know about the
framework limitations.

This patch set tries to solve the issue by adding one flag inside the
trip point: 'irq-mode;'.  The trip point 'passive' declared in DT with
explicit flag 'irq-mode;' will not register itself as polling mode.
Thermal framework will skip it during scheduling next read out work.
The old global-polling-mode-configuration-inside-thermal-zone is still
valid.  Patch set does not break existing design for trip points which
do not have 'irq-mode' flag - they will use polling.

As an example please check patch #10 for Exynos4 SoC family, where there
is 4 HW supported trip points and there is a need of 6. The rest 2 are
declared as 'passive' without 'irq-mode;' flag, which means polling
mode needed for them.

Patch #1 is a small cleanup in thermal framework.

Change log:
v2
- changed description in cover letter
- change commit messages according to Krzysztof comments
- rebase on top of current mainline (v4.20-rc1)

Regards,
Lukasz Luba

Lukasz Luba (11):
  thermal: remove unused function parameter
  thermal: add irq-mode configuration for trip point
  thermal: add new sysfs file for irq-mode
  Doc: thermal: new irq-mode for trip point
  Doc: DT: thermal: new irq-mode for trip point
  arm64: dts: exynos5433: add support for thermal trip irq-mode
  arm64: dts: exynos7: add support for thermal trip irq-mode
  arm: dts: exynos4: add support for thermal trip irq-mode
  arm: dts: exynos5420: add support for thermal trip irq-mode
  arm: dts: exynos5422: add support for thermal trip irq-mode
  arm: dts: exynos5410: add support for thermal trip irq-mode

 .../devicetree/bindings/thermal/thermal.txt        |   7 ++
 Documentation/thermal/sysfs-api.txt                |   9 ++
 arch/arm/boot/dts/exynos4-cpu-thermal.dtsi         |  10 +-
 arch/arm/boot/dts/exynos5410-odroidxu.dts          |  10 +-
 arch/arm/boot/dts/exynos5420-trip-points.dtsi      |  10 +-
 arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |  40 +++++---
 arch/arm64/boot/dts/exynos/exynos5433-tmu.dtsi     | 105 ++++++++++++++-------
 .../arm64/boot/dts/exynos/exynos7-trip-points.dtsi |   8 ++
 drivers/thermal/of-thermal.c                       |  17 ++++
 drivers/thermal/thermal_core.c                     |  16 ++--
 drivers/thermal/thermal_sysfs.c                    |  53 ++++++++++-
 include/linux/thermal.h                            |   5 +
 12 files changed, 226 insertions(+), 64 deletions(-)

Comments

Zhang Rui Dec. 5, 2018, 3:08 p.m. UTC | #1
On 三, 2018-11-07 at 18:09 +0100, Lukasz Luba wrote:
> Hi all,
> 
> This patch set adds a new flag and mechanism in thermal trip points
> in
> DT.  The old implementation in thermal zone in DT sets the same
> configuration for all internal trip points. It does not work for all
> HW.  There are SoCs which support IRQs for some trip points (i.e.
> Exynos 4 has 4 trip points with IRQs). For additional one defined
> inside the thermal zone there is a need of 'polling'. When developer
> adds polling mode settings inside the thermal zone, all the trip
> points will be registered for polling, even those supporting IRQs,
> which does not make sense.

we have two timers, one for polling, and one for passive cooling.
I think we are talking about passive cooling timer only, right?
And the real problem is that we have multiple passive trip points and
only part of them support irq_mode, and we don't want to start the
passive polling timer for all of the passive trip points.

thanks,
rui

>  Thus, developers create workarounds, which
> are confusing for some other developers.  To workaround, 
> people declare some trip points as 'active' (those with IRQ support).
> It allows to bypass polling mode in thermal framework applied for 
> all thermal zone's trip points.
> 
> Thermal framework defines 4 types of trip points. The 'passive' means
> passive cooling using DVFS, 'active' is designed for fan and other
> devices actively changing the outside conditions. Therefore, a
> workaround
> mentioned earlier is confusing when someone does not know about the
> framework limitations.
> 
> This patch set tries to solve the issue by adding one flag inside the
> trip point: 'irq-mode;'.  The trip point 'passive' declared in DT
> with
> explicit flag 'irq-mode;' will not register itself as polling mode.
> Thermal framework will skip it during scheduling next read out work.
> The old global-polling-mode-configuration-inside-thermal-zone is
> still
> valid.  Patch set does not break existing design for trip points
> which
> do not have 'irq-mode' flag - they will use polling.
> 
> As an example please check patch #10 for Exynos4 SoC family, where
> there
> is 4 HW supported trip points and there is a need of 6. The rest 2
> are
> declared as 'passive' without 'irq-mode;' flag, which means polling
> mode needed for them.
> 
> Patch #1 is a small cleanup in thermal framework.
> 
> Change log:
> v2
> - changed description in cover letter
> - change commit messages according to Krzysztof comments
> - rebase on top of current mainline (v4.20-rc1)
> 
> Regards,
> Lukasz Luba
> 
> Lukasz Luba (11):
>   thermal: remove unused function parameter
>   thermal: add irq-mode configuration for trip point
>   thermal: add new sysfs file for irq-mode
>   Doc: thermal: new irq-mode for trip point
>   Doc: DT: thermal: new irq-mode for trip point
>   arm64: dts: exynos5433: add support for thermal trip irq-mode
>   arm64: dts: exynos7: add support for thermal trip irq-mode
>   arm: dts: exynos4: add support for thermal trip irq-mode
>   arm: dts: exynos5420: add support for thermal trip irq-mode
>   arm: dts: exynos5422: add support for thermal trip irq-mode
>   arm: dts: exynos5410: add support for thermal trip irq-mode
> 
>  .../devicetree/bindings/thermal/thermal.txt        |   7 ++
>  Documentation/thermal/sysfs-api.txt                |   9 ++
>  arch/arm/boot/dts/exynos4-cpu-thermal.dtsi         |  10 +-
>  arch/arm/boot/dts/exynos5410-odroidxu.dts          |  10 +-
>  arch/arm/boot/dts/exynos5420-trip-points.dtsi      |  10 +-
>  arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |  40 +++++---
>  arch/arm64/boot/dts/exynos/exynos5433-tmu.dtsi     | 105
> ++++++++++++++-------
>  .../arm64/boot/dts/exynos/exynos7-trip-points.dtsi |   8 ++
>  drivers/thermal/of-thermal.c                       |  17 ++++
>  drivers/thermal/thermal_core.c                     |  16 ++--
>  drivers/thermal/thermal_sysfs.c                    |  53 ++++++++++-
>  include/linux/thermal.h                            |   5 +
>  12 files changed, 226 insertions(+), 64 deletions(-)
>
Lukasz Luba Dec. 5, 2018, 3:33 p.m. UTC | #2
Hi Rui,

On 12/5/18 4:08 PM, Zhang Rui wrote:
> On 三, 2018-11-07 at 18:09 +0100, Lukasz Luba wrote:
>> Hi all,
>>
>> This patch set adds a new flag and mechanism in thermal trip points
>> in
>> DT.  The old implementation in thermal zone in DT sets the same
>> configuration for all internal trip points. It does not work for all
>> HW.  There are SoCs which support IRQs for some trip points (i.e.
>> Exynos 4 has 4 trip points with IRQs). For additional one defined
>> inside the thermal zone there is a need of 'polling'. When developer
>> adds polling mode settings inside the thermal zone, all the trip
>> points will be registered for polling, even those supporting IRQs,
>> which does not make sense.
> 
> we have two timers, one for polling, and one for passive cooling.
> I think we are talking about passive cooling timer only, right?
> And the real problem is that we have multiple passive trip points and
> only part of them support irq_mode, and we don't want to start the
> passive polling timer for all of the passive trip points.
Yes exactly, we don't want to poll all of them by starting 'passive 
polling timer'.

Regards,
Lukasz
> 
> thanks,
> rui
> 
>>   Thus, developers create workarounds, which
>> are confusing for some other developers.  To workaround,
>> people declare some trip points as 'active' (those with IRQ support).
>> It allows to bypass polling mode in thermal framework applied for
>> all thermal zone's trip points.
>>
>> Thermal framework defines 4 types of trip points. The 'passive' means
>> passive cooling using DVFS, 'active' is designed for fan and other
>> devices actively changing the outside conditions. Therefore, a
>> workaround
>> mentioned earlier is confusing when someone does not know about the
>> framework limitations.
>>
>> This patch set tries to solve the issue by adding one flag inside the
>> trip point: 'irq-mode;'.  The trip point 'passive' declared in DT
>> with
>> explicit flag 'irq-mode;' will not register itself as polling mode.
>> Thermal framework will skip it during scheduling next read out work.
>> The old global-polling-mode-configuration-inside-thermal-zone is
>> still
>> valid.  Patch set does not break existing design for trip points
>> which
>> do not have 'irq-mode' flag - they will use polling.
>>
>> As an example please check patch #10 for Exynos4 SoC family, where
>> there
>> is 4 HW supported trip points and there is a need of 6. The rest 2
>> are
>> declared as 'passive' without 'irq-mode;' flag, which means polling
>> mode needed for them.
>>
>> Patch #1 is a small cleanup in thermal framework.
>>
>> Change log:
>> v2
>> - changed description in cover letter
>> - change commit messages according to Krzysztof comments
>> - rebase on top of current mainline (v4.20-rc1)
>>
>> Regards,
>> Lukasz Luba
>>
>> Lukasz Luba (11):
>>    thermal: remove unused function parameter
>>    thermal: add irq-mode configuration for trip point
>>    thermal: add new sysfs file for irq-mode
>>    Doc: thermal: new irq-mode for trip point
>>    Doc: DT: thermal: new irq-mode for trip point
>>    arm64: dts: exynos5433: add support for thermal trip irq-mode
>>    arm64: dts: exynos7: add support for thermal trip irq-mode
>>    arm: dts: exynos4: add support for thermal trip irq-mode
>>    arm: dts: exynos5420: add support for thermal trip irq-mode
>>    arm: dts: exynos5422: add support for thermal trip irq-mode
>>    arm: dts: exynos5410: add support for thermal trip irq-mode
>>
>>   .../devicetree/bindings/thermal/thermal.txt        |   7 ++
>>   Documentation/thermal/sysfs-api.txt                |   9 ++
>>   arch/arm/boot/dts/exynos4-cpu-thermal.dtsi         |  10 +-
>>   arch/arm/boot/dts/exynos5410-odroidxu.dts          |  10 +-
>>   arch/arm/boot/dts/exynos5420-trip-points.dtsi      |  10 +-
>>   arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |  40 +++++---
>>   arch/arm64/boot/dts/exynos/exynos5433-tmu.dtsi     | 105
>> ++++++++++++++-------
>>   .../arm64/boot/dts/exynos/exynos7-trip-points.dtsi |   8 ++
>>   drivers/thermal/of-thermal.c                       |  17 ++++
>>   drivers/thermal/thermal_core.c                     |  16 ++--
>>   drivers/thermal/thermal_sysfs.c                    |  53 ++++++++++-
>>   include/linux/thermal.h                            |   5 +
>>   12 files changed, 226 insertions(+), 64 deletions(-)
>>
> 
>