138 lines
5.3 KiB
Plaintext
138 lines
5.3 KiB
Plaintext
Thermal estimator driver.
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Properties :
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- compatible : Should contain "nvidia,therm-est".
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- polling-period : Polling wait times for thermal estimation, in milliseconds.
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- tc1 : Coefficient 1 for thermal trend calculation.
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- tc2 : Coefficient 2 for thermal trend calculation.
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- node for subdev : Node for subdevice information. Required.
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- use_tmargin : if tmargin algorithm should be used for calculating the
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effective temp. Refer Tmargin section for more info.
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Properties in subdev node : Required.
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- subdev_names : list of strings. It contains list of the name of the therm
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zones used for estimation.
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- node for coeff_set : contains a set of zone specific coefficients+offset.
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This node can be numerous.
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Properties in coeff_set : Required. Can be numerous.
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- toffset : Temperature offset for thermal estimation, in milli-celsius.
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- coeffs : An array of coefficients, the number of entries should be twenty
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per sub device.
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Example:
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therm_est_sensor {
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device_type = "therm-est-subdev";
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polling-period = <1100>;
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tc1 = <10>;
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tc2 = <1>;
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subdev {
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subdev_names = "Tdiode_tegra", "Tboard_tegra";
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coeff_set@0 {
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toffset = <9793>;
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coeffs = <
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2 1 1 1 1 1 1 1 1 1 1 0 1 1 0 0 0 0 (-1) (-7)
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(-11) (-7) (-5) (-3) (-3) (-2) (-1) 0 0 0 1 1 1 2 2 3 4 6 11 18
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>;
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};
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coeff_set@1 {
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toffset = <708>;
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coeffs = <
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-1 -1 1 1 1 1 1 1 1 1 1 0 1 1 0 0 0 (-1) (-3) (-9)
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(-6) (-4) (-1) 0 0 0 0 0 0 0 1 1 1 2 2 5 7 10 17 20
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>;
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};
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};
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};
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Tmargin Algorithm:
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The native max temp algorithm lacks support for accomodating multiple thermal
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fan curves. Tmargin algorithm solves this by calculating the effective
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temperature as a difference from critical temperature of the therm fan est
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group. This allows us to take a union of two fan curves and satisfy the needs
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of both the therm-fan-est groups.
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The algorithm use the effective temperature(crit_temp - sensor_reading) to
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drive the cooling device.
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Properties rules for therm-fan-est dt entry:
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- use_tmargin : To use the tmargin feature.
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- profiles : New profile tmargin should be defined and chosen as default.
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* The trip temperatures need to be given only in ascending order for the
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thermal framework to register therm-fan-est zone. Hence, the dt values
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for active trip temps should be given in ascending values of tmargin
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values.
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* Hysterysis is used only in cooling scenario. Since tmargin is
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considered as a diff wrt crit_Temp, hysterysis values should be taken
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as -ve values.
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Properties rules for fan dt entry:
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- profiles : New profile for tmargin should be defined and chosen as default.
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* The trip temps are considered in a ascending order of tmargin temps.
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Hence, the pwm values should be considered in a descending order of
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pwms.
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* active_steps - The tmargin trip values are considered in the ascending
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order(hence actual trip temps will be in descending order), so the
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pwm mapping should be in the reverse order starting from 255 for
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index 0.
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Example :
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thermal-fan-est {
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compatible = "thermal-fan-est";
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name = "thermal-fan-est";
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status = "okay";
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num_resources = <0>;
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shared_data = <&thermal_fan_est_shared_data>;
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trip_length = <10>;
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use_tmargin;
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profiles {
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default = "tmargin";
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quiet {
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active_trip_temps = <0 50000 63000 72000 81000
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140000 150000 160000 170000 180000>;
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active_hysteresis = <0 18000 8000 8000 8000
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0 0 0 0 0>;
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};
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cool {
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active_trip_temps = <0 35000 53000 62000 73000
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140000 150000 160000 170000 180000>;
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active_hysteresis = <0 9000 8000 8000 9000
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0 0 0 0 0>;
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};
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tmargin {
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active_trip_temps = <0 10000 15000 25000 35000
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45000 55000 65000 75000 105000>;
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active_hysteresis = <0 0 0 0 (-3000)
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(-4000) (-4000) 0 0 0>;
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};
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};
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};
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pwm-fan {
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compatible = "pwm-fan";
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status = "okay";
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#pwm-cells = <1>;
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pwms = <&tegra_pwm4 0 45334>;
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shared_data = <&pwm_fan_shared_data>;
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profiles {
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default = "tmargin";
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quiet {
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state_cap = <8>;
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active_pwm = <0 60 90 120 150 180 210 240 255 255>;
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};
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cool {
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state_cap = <4>;
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active_pwm = <0 77 120 160 255 255 255 255 255 255>;
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};
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tmargin {
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state_cap = <0>;
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active_pwm = <255 255 240 210 180 150 120 90 60 0>;
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};
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};
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};
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