[RFC,0/9] Add CPU based scaling support to Passive governor

Message

Sibi Sankar March 28, 2019, 3:28 p.m. UTC

This RFC series aims to add cpu based scaling support to the passive
governor and scale DDR with a generic interconnect bandwidth based
devfreq driver on SDM845 SoC. This series achieves similar functionality
to Georgi's Patch series (https://patchwork.kernel.org/cover/10850817/)
and can be used with MSM8916/MSM8996/QCS404 SoCs.

[patches 1,6 - Add and export export helpers to get avg/peak bandwidth and
 update voltage of an disabled opp respectively]

[patch 3 - Adds cpu based scaling support to passive governor]
To achieve this, it listens to CPU frequency transition notifiers
to keep itself up to date on the current CPU frequency.
To decide the frequency of the device, the governor depends one of
the following:
* Constructs a CPU frequency to device frequency mapping table from
  required-opps property of the devfreq device's opp_table
* Scales the device frequency in proportion to the CPU frequency by
  performing interpolation.

[patch 7 - Parses and updates opps from the frequency/voltage read from
 the look up tables]

The patch series depends on opp-bw-MBs bindings introduced in:
https://patchwork.kernel.org/cover/10850817/

Saravana Kannan (2):
  PM / devfreq: Add cpu based scaling support to passive_governor
  PM / devfreq: Add devfreq driver for interconnect bandwidth voting

Sibi Sankar (7):
  OPP: Add and export helpers to get avg/peak bw
  OPP: Export a number of helpers to prevent code duplication
  dt-bindings: devfreq: Add bindings for devfreq dev-icbw driver
  OPP: Add and export helper to update voltage
  cpufreq: qcom: Add support to update cpu node's OPP tables
  arm64: dts: qcom: sdm845: Add cpu OPP tables
  arm64: dts: qcom: sdm845: Add nodes for icbw driver and opp tables

 .../devicetree/bindings/devfreq/icbw.txt      | 146 +++++++++
 arch/arm64/boot/dts/qcom/sdm845.dtsi          | 262 +++++++++++++++++
 drivers/cpufreq/qcom-cpufreq-hw.c             |  29 +-
 drivers/devfreq/Kconfig                       |  19 ++
 drivers/devfreq/Makefile                      |   1 +
 drivers/devfreq/devfreq_icbw.c                | 132 +++++++++
 drivers/devfreq/governor_passive.c            | 276 +++++++++++++++++-
 drivers/opp/core.c                            | 100 +++++++
 drivers/opp/of.c                              |  13 +-
 include/linux/devfreq.h                       |  43 ++-
 include/linux/pm_opp.h                        |  35 +++
 11 files changed, 1044 insertions(+), 12 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/devfreq/icbw.txt
 create mode 100644 drivers/devfreq/devfreq_icbw.c

Comments

Sibi Sankar April 11, 2019, 7:02 a.m. UTC | #1

On 2019-03-28 20:58, Sibi Sankar wrote:
> This RFC series aims to add cpu based scaling support to the passive
> governor and scale DDR with a generic interconnect bandwidth based
> devfreq driver on SDM845 SoC. This series achieves similar 
> functionality
> to Georgi's Patch series (https://patchwork.kernel.org/cover/10850817/)
> and can be used with MSM8916/MSM8996/QCS404 SoCs.
> 
> [patches 1,6 - Add and export export helpers to get avg/peak bandwidth 
> and
>  update voltage of an disabled opp respectively]
> 
> [patch 3 - Adds cpu based scaling support to passive governor]
> To achieve this, it listens to CPU frequency transition notifiers
> to keep itself up to date on the current CPU frequency.
> To decide the frequency of the device, the governor depends one of
> the following:
> * Constructs a CPU frequency to device frequency mapping table from
>   required-opps property of the devfreq device's opp_table
> * Scales the device frequency in proportion to the CPU frequency by
>   performing interpolation.

Had a discussion with Viresh and Georgi,
Viresh pointed out cpu based scaling can
be done in a better way by placing the
required-opps in the cpu opp table and
with some changes in the core so dropping
the idea of cpufreq integration into passive
governor for now.

> 
> [patch 7 - Parses and updates opps from the frequency/voltage read from
>  the look up tables]
> 
> The patch series depends on opp-bw-MBs bindings introduced in:
> https://patchwork.kernel.org/cover/10850817/
> 
> Saravana Kannan (2):
>   PM / devfreq: Add cpu based scaling support to passive_governor
>   PM / devfreq: Add devfreq driver for interconnect bandwidth voting
> 
> Sibi Sankar (7):
>   OPP: Add and export helpers to get avg/peak bw
>   OPP: Export a number of helpers to prevent code duplication
>   dt-bindings: devfreq: Add bindings for devfreq dev-icbw driver
>   OPP: Add and export helper to update voltage
>   cpufreq: qcom: Add support to update cpu node's OPP tables
>   arm64: dts: qcom: sdm845: Add cpu OPP tables
>   arm64: dts: qcom: sdm845: Add nodes for icbw driver and opp tables
> 
>  .../devicetree/bindings/devfreq/icbw.txt      | 146 +++++++++
>  arch/arm64/boot/dts/qcom/sdm845.dtsi          | 262 +++++++++++++++++
>  drivers/cpufreq/qcom-cpufreq-hw.c             |  29 +-
>  drivers/devfreq/Kconfig                       |  19 ++
>  drivers/devfreq/Makefile                      |   1 +
>  drivers/devfreq/devfreq_icbw.c                | 132 +++++++++
>  drivers/devfreq/governor_passive.c            | 276 +++++++++++++++++-
>  drivers/opp/core.c                            | 100 +++++++
>  drivers/opp/of.c                              |  13 +-
>  include/linux/devfreq.h                       |  43 ++-
>  include/linux/pm_opp.h                        |  35 +++
>  11 files changed, 1044 insertions(+), 12 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/devfreq/icbw.txt
>  create mode 100644 drivers/devfreq/devfreq_icbw.c