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powercap: Add Power Limit4 support

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Modern Intel Mobile platforms support power limit4 (PL4), which is
the SoC package level maximum power limit (in Watts). It can be used
to preemptively limits potential SoC power to prevent power spikes
from tripping the power adapter and battery over-current protection.
This patch enables this feature by exposing package level peak power
capping control to userspace via RAPL sysfs interface. With this,
application like DTPF can modify PL4 power limit, the similar way
of other package power limit (PL1).
As this feature is not tested on previous generations, here it is
enabled only for the platform that has been verified to work,
for safety concerns.

Signed-off-by: Sumeet Pawnikar <sumeet.r.pawnikar@intel.com>
Co-developed-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Tested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Sumeet Pawnikar
2020-07-16 23:14:55 +05:30
committed by Rafael J. Wysocki
parent 0735069c5e
commit 8365a898fe
4 changed files with 81 additions and 8 deletions
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Documentation/power/powercap/powercap.rst
+10 -5
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@@ -167,11 +167,13 @@ For example::
package-0
---------
The Intel RAPL technology allows two constraints, short term and long term,
with two different time windows to be applied to each power zone. Thus for
each zone there are 2 attributes representing the constraint names, 2 power
limits and 2 attributes representing the sizes of the time windows. Such that,
constraint_j_* attributes correspond to the jth constraint (j = 0,1).
Depending on different power zones, the Intel RAPL technology allows
one or multiple constraints like short term, long term and peak power,
with different time windows to be applied to each power zone.
All the zones contain attributes representing the constraint names,
power limits and the sizes of the time windows. Note that time window
is not applicable to peak power. Here, constraint_j_* attributes
correspond to the jth constraint (j = 0,1,2).
For example::
@@ -181,6 +183,9 @@ For example::
constraint_1_name
constraint_1_power_limit_uw
constraint_1_time_window_us
constraint_2_name
constraint_2_power_limit_uw
constraint_2_time_window_us
Power Zone Attributes
=====================