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| author | Bjorn Andersson <bjorn.andersson@linaro.org> | 2022-05-23 16:37:19 -0700 |
|---|---|---|
| committer | Pavel Machek <pavel@ucw.cz> | 2022-05-24 22:08:10 +0200 |
| commit | e98a860f65428a3cae7ed7b3e8ebcf6320d7fc5e (patch) | |
| tree | a63712ae933948a5b27eca0daba1f706cbac3c4c /Documentation/leds | |
| parent | 73bce575ed90c752eaa4b2b9a70860481d58d240 (diff) | |
leds: qcom-lpg: Require pattern to follow documentation
The leds-trigger-pattern documentation describes how the brightness of
the LED should transition linearly from one brightness value to the
next, over the given delta_t.
But the pattern engine in the Qualcomm LPG hardware only supports
holding the brightness for each entry for the period.
This subset of patterns can be represented in the leds-trigger-pattern
by injecting zero-time transitions after each entry in the pattern,
resulting in a pattern that pattern that can be rendered by the LPG.
Rework LPG pattern interface to require these zero-time transitions, to
make it comply with this subset of patterns and reject the patterns it
can't render.
Fixes: 24e2d05d1b68 ("leds: Add driver for Qualcomm LPG")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Diffstat (limited to 'Documentation/leds')
| -rw-r--r-- | Documentation/leds/leds-qcom-lpg.rst | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/Documentation/leds/leds-qcom-lpg.rst b/Documentation/leds/leds-qcom-lpg.rst index f12416f02dd8..de7ceead9337 100644 --- a/Documentation/leds/leds-qcom-lpg.rst +++ b/Documentation/leds/leds-qcom-lpg.rst @@ -35,11 +35,13 @@ Specify a hardware pattern for a Qualcomm LPG LED. The pattern is a series of brightness and hold-time pairs, with the hold-time expressed in milliseconds. The hold time is a property of the pattern and must therefor be identical for each element in the pattern (except for the pauses -described below). +described below). As the LPG hardware is not able to perform the linear +transitions expected by the leds-trigger-pattern format, each entry in the +pattern must be followed a zero-length entry of the same brightness. Simple pattern:: - "255 500 0 500" + "255 500 255 0 0 500 0 0" ^ | @@ -54,7 +56,7 @@ in the pattern, the so called "low pause" and "high pause". Low-pause pattern:: - "255 1000 0 500 255 500 0 500" + "255 1000 255 0 0 500 0 0 255 500 255 0 0 500 0 0" ^ | |