“How to modify the panel backlight”的版本间的差异
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− | {{ | + | First identify the backlight device linked to your panel, thanks to the sysfs: |
+ | {{Board$}} ls /sys/class/backlight | ||
+ | 5a000000.dsi.0 | ||
− | + | In the above example, there is a single entry named "5a000000.dsi.0", which is '''replaced by "*"''' in the below command. | |
− | + | ||
− | + | ||
+ | To adjust the panel backlight, enter the following command: | ||
+ | {{Board$}} echo '''32''' > /sys/class/backlight/*/'''brightness''' # set the dsi panel backlight to the value '''32''' | ||
+ | Note: Only values between 0 and '''max_brightness''' must be used. | ||
+ | |||
+ | To get the maximum panel backlight value, enter: | ||
+ | {{Board$}} cat /sys/class/backlight/*/'''max_brightness''' | ||
+ | 255 | ||
+ | |||
+ | To get the actual panel backlight value, enter: | ||
+ | {{Board$}} cat /sys/class/backlight/*/'''actual_brightness''' | ||
+ | 32 | ||
+ | |||
+ | |||
+ | Use one of the following commands to quickly test the panel backlight: | ||
+ | {{Board$}} export bl=/sys/class/backlight/5a000000.dsi.0/brightness | ||
+ | |||
+ | {{Board$}} # switch on/off test | ||
+ | {{Board$}} (while true; do echo 0 > $bl; sleep 0.5; echo 255 > $bl; sleep 0.5; done) | ||
+ | |||
+ | {{Board$}} # slow 32-step tests | ||
+ | {{Board$}} (i=0; while true; do i=$(((i+32)%256)); echo $i > $bl; sleep 0.5; done) | ||
+ | |||
+ | {{Board$}} # fast 1-step test | ||
+ | {{Board$}} (i=0; while true; do i=$(((i+1)%256)); echo $i > $bl; done) | ||
+ | |||
+ | |||
+ | <noinclude> | ||
+ | {{PublicationRequestId | 10715 | 2019-02-18 | AnneJ}} | ||
+ | [[Category:How to run use cases]] | ||
+ | [[Category:DRM KMS]] | ||
+ | </noinclude> |
2020年5月8日 (五) 22:31的最新版本
First identify the backlight device linked to your panel, thanks to the sysfs:
Board $> ls /sys/class/backlight 5a000000.dsi.0
In the above example, there is a single entry named "5a000000.dsi.0", which is replaced by "*" in the below command.
To adjust the panel backlight, enter the following command:
Board $> echo 32 > /sys/class/backlight/*/brightness # set the dsi panel backlight to the value 32
Note: Only values between 0 and max_brightness must be used.
To get the maximum panel backlight value, enter:
Board $> cat /sys/class/backlight/*/max_brightness 255
To get the actual panel backlight value, enter:
Board $> cat /sys/class/backlight/*/actual_brightness 32
Use one of the following commands to quickly test the panel backlight:
Board $> export bl=/sys/class/backlight/5a000000.dsi.0/brightness Board $> # switch on/off test Board $> (while true; do echo 0 > $bl; sleep 0.5; echo 255 > $bl; sleep 0.5; done) Board $> # slow 32-step tests Board $> (i=0; while true; do i=$(((i+32)%256)); echo $i > $bl; sleep 0.5; done) Board $> # fast 1-step test Board $> (i=0; while true; do i=$(((i+1)%256)); echo $i > $bl; done)
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