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SubjectRe: [PATCH] PM / devfreq: Generic cpufreq governor
On 2018-07-27 20:56, Saravana Kannan wrote:
> Many CPU architectures have caches that can scale independent of the
> CPUs.
> Frequency scaling of the caches is necessary to make sure the cache is
> not
> a performance bottleneck that leads to poor performance and power. The
> same
> idea applies for RAM/DDR.
>
> To achieve this, this patch adds a generic devfreq governor that can
> listen
> to the frequency transitions of each CPU frequency domain and then
> adjusts
> the frequency of the cache (or any devfreq device) based on the
> frequency
> of the CPUs.
>
> To decide the frequency of the device, the governor does one of the
> following:
>
> * Uses a CPU frequency to device frequency mapping table
> - Either one mapping table used for all CPU freq policies (typically
> used
> for system with homogeneous cores/clusters that have the same OPPs.
> - One mapping table per CPU freq policy (typically used for ASMP
> systems
> with heterogeneous CPUs with different OPPs)
>
> OR
>
> * Scales the device frequency in proportion to the CPU frequency. So,
> if
> the CPUs are running at their max frequency, the device runs at its
> max
> frequency. If the CPUs are running at their min frequency, the
> device
> runs at its min frequency. And interpolated for frequencies in
> between.
>
> Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
> ---
> .../bindings/devfreq/devfreq-cpufreq.txt | 53 ++
> drivers/devfreq/Kconfig | 8 +
> drivers/devfreq/Makefile | 1 +
> drivers/devfreq/governor_cpufreq.c | 583
> +++++++++++++++++++++
> 4 files changed, 645 insertions(+)
> create mode 100644
> Documentation/devicetree/bindings/devfreq/devfreq-cpufreq.txt
> create mode 100644 drivers/devfreq/governor_cpufreq.c
>
> diff --git
> a/Documentation/devicetree/bindings/devfreq/devfreq-cpufreq.txt
> b/Documentation/devicetree/bindings/devfreq/devfreq-cpufreq.txt
> new file mode 100644
> index 0000000..6537538

MyungJoo, Chanwoo,

Thoughts? Good enough to merge?

Rob,

DT review? I know this DT documentation should be a separate patch, but
I've kept it here for context. I can split it up once the code and the
binding have been agreed to.

Thanks,
Saravana

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