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authorSumeet Pawnikar <sumeet.r.pawnikar@intel.com>2020-07-16 20:44:55 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-07-27 15:17:36 +0300
commit8365a898fe53f85529566501d3b3d88640b3975e (patch)
tree7984171ae5c65ba430b85596592bbe39b4b4a1ea /Documentation
parent0735069c5e49d3f4f5f92669fcc3882500c118e5 (diff)
downloadlinux-8365a898fe53f85529566501d3b3d88640b3975e.tar.xz
powercap: Add Power Limit4 support
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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/power/powercap/powercap.rst15
1 files changed, 10 insertions, 5 deletions
diff --git a/Documentation/power/powercap/powercap.rst b/Documentation/power/powercap/powercap.rst
index 7ae3b44c7624..e75d12596dac 100644
--- a/Documentation/power/powercap/powercap.rst
+++ b/Documentation/power/powercap/powercap.rst
@@ -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
=====================