76 lines
3.1 KiB
Plaintext
76 lines
3.1 KiB
Plaintext
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Bindings for a fan connected to the PWM lines
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Properties details:
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- compatible : "pwm-fan"
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- pwms : the PWM that is used to control the PWM fan
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- shared_data
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- active_steps : Entries for references in active_rpm[], active_pwm[], active_rru[], active_rrd[]
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- active_rru : This value is kept on added to cur_pwm till it reaches at
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next active step from the table. This is repeated until cur_pwm
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value reaches target_pwm
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- active_rrd : This value is kept on subtracted from cur_pwm till it reaches at
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previous active step from the table. This is repeated until cur_pwm
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value reaches target_pwm
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- state_cap_lookup : Index to refer in active_pwm[]
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- pwm_period : To derive duty cycle
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- pwm_id : Assigned PWM controller id to tegra fan
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Same as mentioned id in pwms. In pwms, the id starts from 1
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pwm_id in pfsd, the id starts from 0
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- step_time : Time taken for each step during rru/rrd
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- state_cap : Capping state value out of available active_steps
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- active_pwm_max : Max pwm value (256)
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- pwm_gpio : GPIO pin used for pwm
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- use_tach_feedback : Enable the tachometer feedback logic. If a pwm set
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request is raised, two worker threads are scheduled.
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One for setting the pwm value and one for correcting
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the pwm based on desired rpm for the pwm requested.
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The tachometer readings are validated for 16 consecutive times
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before the feedbacklogic bails out successfully.
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If the rpm validation fails, the second worker thread
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keeps updating the pwm using the rru/rrd values.
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- rpm_ramp_time_ms : The rpm validation worker thread waits for the given
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value(milliseconds) after scheduling the pwm set
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worker thread.
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- rpm_diff_tolerance : How much rpm diff is to be tolerated by the rpm
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validation logic.
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- rpm_valid_retry_count : In case the fan rpm is in limit, how many times
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should the validation logic test for regression.
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- rpm_valid_retry_delay : How much delay to be used during the validation
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retries after the rpm is brought to threshold values
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- rpm_invalid_retry_delay : In case the rpm expected and tachometer reading
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values mismatch, how much delay should be used for
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next validation.
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- use_tmargin : If Tmargin algorithm is being used in therm_fan_est
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driver. This node needs to be enabled for the pwm fan
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driver to work properly.
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- is_always_on : Enable if the fan is always on.
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Example:
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pwm_fan_shared_data: pfsd {
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status = "okay";
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num_resources = <0>;
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active_steps = <10>;
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active_rpm = <0 1000 2000 3000 4000 5000 6000 7000 10000 11000>;
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active_rru = <40 2 1 1 1 1 1 1 1 1>;
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active_rrd = <40 2 1 1 1 1 1 1 1 1>;
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state_cap_lookup = <2 2 2 2 3 3 3 4 4 4>;
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pwm_period = <45334>;
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pwm_id = <3>;
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step_time = <100>; /* mesecs */
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state_cap = <7>;
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active_pwm_max = <256>;
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pwm_gpio = <&tegra_aon_gpio TEGRA_AON_GPIO(V, 6) GPIO_ACTIVE_LOW>; /* TEGRA_MAIN_GPIO_PV6 */
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};
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pwm-fan {
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status = "okay";
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compatible = "pwm-fan";
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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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active_pwm = <0 80 120 160 255 255 255 255 255 255>;
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};
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};
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