driver-api/thermal/power_allocator.rst

6 -----------
20 --------------
23 Proportional-Integral-Derivative controller (PID controller) with
29    -  e = desired_temperature - current_temperature
30    -  err_integral is the sum of previous errors
31    -  diff_err = e - previous_error
39        |              +----------+   +---+
40        |       +----->| diff_err |-->| X |------+
41        |       |      +----------+   +---+      |
47      +---+     |      +-------+      +---+    +---+   +---+   +----------+
48      | S |-----+----->| sum e |----->| X |--->| S |-->| S |-->|power     |
49      +---+     |      +-------+      +---+    +---+   +---+   |allocation|
50        ^       |                                ^             +----------+
52        |       |        +---+                   |                |     |
53        |       +------->| X |-------------------+                v     v
54        |                +---+                               granted performance
61 -----------------
70 to the speed-grade of the silicon.  `sustainable_power` is therefore
79 thermal-zone.  For example::
81 	thermal-zones {
83 			polling-delay = <1000>;
84 			polling-delay-passive = <100>;
85 			sustainable-power = <2500>;
101 -------------
114 available capacity at a low temperature.  On the other hand, a high
115 value of `k_pu` will result in the governor granting very high power
120     2 * sustainable_power / (desired_temperature - switch_on_temp)
126     sustainable_power / (desired_temperature - switch_on_temp)
138 an estimate, which is the reason for closed-loop control such as this.
142     P_max = 2 * sustainable_power * (T_set - T) / (T_set - T_on) +
147     - T_set is the desired temperature
148     - T is the current temperature
149     - T_on is the switch on temperature
154     P_max = 2 * sustainable_power * (T_set - T_on) / (T_set - T_on) +
163 -----------------------
175 ---
201 success, -E* on failure.  This is currently used by the power
221 milliwatts and store it in @power.  It should return 0 on success, -E*
239 -E* on failure.  This is currently used by the thermal core to convert
246 ----------------------
249 devices.  They express the relative power efficiency of different
251 efficiency.  Weighting is relative such that if each cooling device
254 the same kind of compute, but with different efficiency.  For example,
261 as the `contribution` property of each map in the `cooling-maps` node.
271 governor, step-wise will also misbehave if you call its throttle()
280 thermal zone should have power values reported either in milli-Watts