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* pwm_bl add framebuffer from fbcon
@ 2018-11-20 10:32 cnegris01
  2018-11-20 10:32 ` Christian N
  0 siblings, 1 reply; 2+ messages in thread
From: cnegris01 @ 2018-11-20 10:32 UTC (permalink / raw)
  To: kernelnewbies

Hi All

First at all I introduce my usecase
-My board based on ARM (OMPA4) can get a custom splash screen on booting
using fbcon.
-By Device Tree I can configure screen backlight with desired level.

i'm trying to turn on backlight when splash screen is displayed and not
before to avoid "white flashes".

I read
Documentation/devicetree/bindings/pwm/pwm.txt
Documentation/devicetree/bindings/leds/pwm-backlight.txt
Documentation/fb/...
https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html

Also I noticed that pwm_bl has pwm_backlight_check_fb operation, but I
didnt find a clear way to relate frame buffer used by fbcon with pwm_bl
related functions or how to customize by DT or kernel config which frame
buffer should be used by pwm_bl to turn on when valid data is ready in fb

Any hints will be apreciated.

Regards
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* pwm_bl add framebuffer from fbcon
  2018-11-20 10:32 pwm_bl add framebuffer from fbcon cnegris01
@ 2018-11-20 10:32 ` Christian N
  0 siblings, 0 replies; 2+ messages in thread
From: Christian N @ 2018-11-20 10:32 UTC (permalink / raw)
  To: kernelnewbies

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Hi All

First at all I introduce my usecase
-My board based on ARM (OMPA4) can get a custom splash screen on booting
using fbcon.
-By Device Tree I can configure screen backlight with desired level.

i'm trying to turn on backlight when splash screen is displayed and not
before to avoid "white flashes".

I read
Documentation/devicetree/bindings/pwm/pwm.txt
Documentation/devicetree/bindings/leds/pwm-backlight.txt
Documentation/fb/...
https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html

Also I noticed that pwm_bl has pwm_backlight_check_fb operation, but I
didnt find a clear way to relate frame buffer used by fbcon with pwm_bl
related functions or how to customize by DT or kernel config which frame
buffer should be used by pwm_bl to turn on when valid data is ready in fb

Any hints will be apreciated.

Regards

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<div dir="ltr"><div dir="ltr"><div>Hi All</div><div><br></div><div>First at all I introduce my usecase</div><div>-My board based on ARM (OMPA4) can get a custom splash screen on booting using fbcon. <br></div><div>-By Device Tree I can configure screen backlight with desired level.</div><div><br></div><div>i&#39;m trying to turn on backlight when splash screen is displayed and not before to avoid &quot;white flashes&quot;.</div><div><br></div><div>I read <br></div><div>Documentation/devicetree/bindings/pwm/pwm.txt</div><div>Documentation/devicetree/bindings/leds/pwm-backlight.txt</div><div>Documentation/fb/...</div><div></div><div><a href="https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html">https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html</a></div><div><br></div><div>Also I noticed that pwm_bl has pwm_backlight_check_fb operation, but I didnt find a clear way to relate frame buffer used by fbcon with pwm_bl related functions or how to customize by DT or kernel config which frame buffer should be used by pwm_bl to turn on when valid data is ready in fb<br></div><div><br></div><div>Any hints will be apreciated.</div><div><br></div><div>Regards<br></div><div> <br></div></div></div>

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2018-11-20 10:32 pwm_bl add framebuffer from fbcon cnegris01
2018-11-20 10:32 ` Christian N

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