From mboxrd@z Thu Jan  1 00:00:00 1970
From: cnegris01@gmail.com (Christian N)
Date: Tue, 20 Nov 2018 07:32:34 -0300
Subject: pwm_bl add framebuffer from fbcon
Message-ID: <CAPNHxoHZqpzPQrAg4pMrhXe254ihyPK+-t=hyRzksifROwer+A@mail.gmail.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

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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From: Christian N <cnegris01@gmail.com>
Date: Tue, 20 Nov 2018 07:32:34 -0300
Message-ID:
 <CAPNHxoHZqpzPQrAg4pMrhXe254ihyPK+-t=hyRzksifROwer+A@mail.gmail.com>
Subject: pwm_bl add framebuffer from fbcon
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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=3D"ltr"><div dir=3D"ltr"><div>Hi All</div><div><br></div><div>Firs=
t at all I introduce my usecase</div><div>-My board based on ARM (OMPA4) ca=
n get a custom splash screen on booting using fbcon. <br></div><div>-By Dev=
ice 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 displ=
ayed 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=3D"https://www.kernel.or=
g/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 re=
lated functions or how to customize by DT or kernel config which frame buff=
er 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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