fan_speed

Source code: fan_speed.py

A factory test to ensure the functionality of CPU fan.

Description

It provides two types of test:

1. target_rpm mode

2. spin_max_then_half mode.

For mode B, it first spins fan up to a max_rpm to get an empirical maximum fan rpm; then it runs mode A with half of the empirical max rpm as target_rpm.

In mode A, the steps are:

1. Sets the fan speed to a target RPM.

2. Monitors the fan speed for a given period (duration_secs) with sampling interval (probe_interval_secs). Then it takes average of the latest num_samples_to_use samples as the stabilized fan speed reading.

3. Checks that the averaged reading is within range [target_rpm - error_margin, target_rpm + error_margin].

Some system services like dptf may change the fan speed while testing so users have to disable them with test object option “disable_services”. See Examples.

Test Procedure

This is an automatic test that doesn’t need any user interaction.

Dependency

• Device API cros.factory.device.fan.

Examples

An example:

{
  "pytest_name": "fan_speed",
  "label": "Fan Speed",
  "run_if": "constants.has_fan",
  "disable_services": [
    "dptf"
  ],
  "args": {
    "probe_interval_secs": 0.2,
    "target_rpm": [
      3000,
      4500,
      6000
    ],
    "error_margin": 300
  }
}

If you prefer to use 7% as error margin:

{
  "pytest_name": "fan_speed",
  "label": "Fan Speed",
  "run_if": "constants.has_fan",
  "disable_services": [
    "dptf"
  ],
  "args": {
    "probe_interval_secs": 0.2,
    "target_rpm": [
      3000,
      4500,
      6000
    ],
    "error_margin": 7,
    "error_margin_use_percentage": true
  }
}

Test Arguments

Name	Type	Description
target_rpm	int, list	(optional; default: 0) A list of target RPM to set during test.Unused if spin_max_then_half is set.
error_margin	int	(optional; default: 200) Fail the test if actual fan speed is off the target by the margin default in units of RPM
duration_secs	int, float	(optional; default: 10) Duration of monitoring fan speed in seconds.
spin_max_then_half	bool	(optional; default: False) If True, spin the fan to max_rpm, measure the actual reading, and set fan speed to half of actual max speed. Note that if True, target_rpm is invalid.
max_rpm	int	(optional; default: 10000) A relatively high RPM for probing maximum fan speed. It is used when spin_max_then_half=True.
probe_interval_secs	float	(optional; default: 0.2) Interval of probing fan speed in seconds.
num_samples_to_use	int	(optional; default: 5) Number of lastest samples to count average as stablized speed.
speed_use_percentage	bool	(optional; default: False) Use percentage to set fan speed
error_margin_use_percentage	bool	(optional; default: False) Use percentage to set error margin
fan_id	int, None	(optional; default: None) The ID of fan to test, use None to test all fans.