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- Spelling s/brigntess/brightness/, - Double "use". Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
82 lines
3 KiB
Text
82 lines
3 KiB
Text
What: /sys/class/leds/<led>/pattern
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Date: September 2018
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KernelVersion: 4.20
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Description:
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Specify a software pattern for the LED, that supports altering
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the brightness for the specified duration with one software
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timer. It can do gradual dimming and step change of brightness.
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The pattern is given by a series of tuples, of brightness and
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duration (ms). The LED is expected to traverse the series and
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each brightness value for the specified duration. Duration of
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0 means brightness should immediately change to new value, and
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writing malformed pattern deactivates any active one.
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1. For gradual dimming, the dimming interval now is set as 50
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milliseconds. So the tuple with duration less than dimming
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interval (50ms) is treated as a step change of brightness,
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i.e. the subsequent brightness will be applied without adding
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intervening dimming intervals.
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The gradual dimming format of the software pattern values should be:
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"brightness_1 duration_1 brightness_2 duration_2 brightness_3
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duration_3 ...". For example:
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echo 0 1000 255 2000 > pattern
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It will make the LED go gradually from zero-intensity to max (255)
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intensity in 1000 milliseconds, then back to zero intensity in 2000
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milliseconds:
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LED brightness
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^
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255-| / \ / \ /
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| / \ / \ /
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| / \ / \ /
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| / \ / \ /
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0-| / \/ \/
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+---0----1----2----3----4----5----6------------> time (s)
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2. To make the LED go instantly from one brightness value to another,
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we should use zero-time lengths (the brightness must be same as
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the previous tuple's). So the format should be:
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"brightness_1 duration_1 brightness_1 0 brightness_2 duration_2
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brightness_2 0 ...". For example:
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echo 0 1000 0 0 255 2000 255 0 > pattern
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It will make the LED stay off for one second, then stay at max brightness
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for two seconds:
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LED brightness
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^
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255-| +---------+ +---------+
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0-| -----+ +----+ +----
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+---0----1----2----3----4----5----6------------> time (s)
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What: /sys/class/leds/<led>/hw_pattern
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Date: September 2018
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KernelVersion: 4.20
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Description:
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Specify a hardware pattern for the LED, for LED hardware that
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supports autonomously controlling brightness over time, according
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to some preprogrammed hardware patterns. It deactivates any active
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software pattern.
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Since different LED hardware can have different semantics of
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hardware patterns, each driver is expected to provide its own
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description for the hardware patterns in their ABI documentation
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file.
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What: /sys/class/leds/<led>/repeat
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Date: September 2018
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KernelVersion: 4.20
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Description:
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Specify a pattern repeat number. -1 means repeat indefinitely,
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other negative numbers and number 0 are invalid.
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This file will always return the originally written repeat
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number.
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