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@xxxxxxxxxxxxxx>
---
.../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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