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SubjectRe: [PATCH RFC 0/9] Add CPU based scaling support to Passive governor
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

--
-- Sibi Sankar --
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project.

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