BackLight - Revision history

JulienB: /* Usage */

2017-07-18T22:17:36Z

Usage

← Older revision		Revision as of 00:17, 19 July 2017
Line 33:		Line 33:

	\|\|<pre class="apf">		\|\|<pre class="apf">
	export BACK_IF=~~lcd~~		export BACK_IF=lcd_backlight
	</pre>		</pre>

JulienB: /* Usage */

2016-12-23T15:45:32Z

Usage

← Older revision		Revision as of 17:45, 23 December 2016
Line 12:		Line 12:
	==Usage==		==Usage==

	On your APF, load the module (not needed on [[APF6]]):		On your APF, load the module (not needed on [[APF6]] and [[OPOS6UL]]):
	<pre class="apf">		<pre class="apf">
	# modprobe imx_bl		# modprobe imx_bl
Line 21:		Line 21:
	{\| border="1" cellpadding="10" cellspacing="0" summary="PWM usage depending on kernel version" class="wikitable"		{\| border="1" cellpadding="10" cellspacing="0" summary="PWM usage depending on kernel version" class="wikitable"
	\|- style="background:#efefef;" align="center"		\|- style="background:#efefef;" align="center"
	! APF27/51/28 \|\| APF6		! APF27/51/28 \|\| APF6 \|\| OPOS6UL
	\|-----		\|-----

Line 30:		Line 30:
	\|\|<pre class="apf">		\|\|<pre class="apf">
	export BACK_IF=backlight_lcd		export BACK_IF=backlight_lcd
			</pre>

			\|\|<pre class="apf">
			export BACK_IF=lcd
	</pre>		</pre>

Line 49:		Line 53:
	# cat /sys/class/backlight/$BACK_IF/max_brightness		# cat /sys/class/backlight/$BACK_IF/max_brightness
	</pre>		</pre>
	* To change the brightness:		* To change the brightness (X depends on previous allowed brightnesses):
	<pre class="apf">		<pre class="apf">
	# echo ~~100~~ > /sys/class/backlight/$BACK_IF/brightness		# echo X > /sys/class/backlight/$BACK_IF/brightness
	</pre>		</pre>

JulienB: /* Usage */

2016-04-15T16:29:37Z

Usage

← Older revision		Revision as of 18:29, 15 April 2016
Line 43:		Line 43:
	* To see the actual brightness:		* To see the actual brightness:
	<pre class="apf">		<pre class="apf">
	# cat /sys/class/backlight/~~imx-bl~~/actual_brightness		# cat /sys/class/backlight/$BACK_IF/actual_brightness
	</pre>		</pre>
	* To see the max allowed brightness:		* To see the max allowed brightness:

JulienB: /* Usage */

2016-04-15T16:28:40Z

Usage

← Older revision		Revision as of 18:28, 15 April 2016
Line 12:		Line 12:
	==Usage==		==Usage==

	On your APF, load the module:		On your APF, load the module (not needed on [[APF6]]):
	<pre class="apf">		<pre class="apf">
	# modprobe imx_bl		# modprobe imx_bl
	i.MX Backlight driver v0.X initialized.		i.MX Backlight driver v0.X initialized.
	</pre>		</pre>

			* Depending on your platform, backlight interface may have a different name, so let's define an envt variable to ease further instructions:
			{\| border="1" cellpadding="10" cellspacing="0" summary="PWM usage depending on kernel version" class="wikitable"
			\|- style="background:#efefef;" align="center"
			! APF27/51/28 \|\| APF6
			\|-----

			\|<pre class="apf">
			export BACK_IF=imx-bl
			</pre>

			\|\|<pre class="apf">
			export BACK_IF=backlight_lcd
			</pre>

			\|}

	All backlight controls are done through the ''/sys'' interface:		All backlight controls are done through the ''/sys'' interface:
	<pre class="apf">		<pre class="apf">
	# ls /sys/class/backlight/~~imx-bl~~/		# ls /sys/class/backlight/$BACK_IF/
	actual_brightness max_brightness subsystem		actual_brightness max_brightness subsystem
	brightness power uevent		brightness power uevent
Line 31:		Line 47:
	* To see the max allowed brightness:		* To see the max allowed brightness:
	<pre class="apf">		<pre class="apf">
	# cat /sys/class/backlight/~~imx-bl~~/max_brightness		# cat /sys/class/backlight/$BACK_IF/max_brightness
	</pre>		</pre>
	* To change the brightness:		* To change the brightness:
	<pre class="apf">		<pre class="apf">
	# echo 100 > /sys/class/backlight/~~imx-bl~~/brightness		# echo 100 > /sys/class/backlight/$BACK_IF/brightness
	</pre>		</pre>

Salocin68: /* Introduction */

2010-08-15T15:48:54Z

Introduction

← Older revision		Revision as of 17:48, 15 August 2010
Line 3:		Line 3:
	==Introduction==		==Introduction==

	Backlight control is done through the i.~~MXL/i.MX27~~ integrated backlight PWM (inside LCDC module). The output signal of this PWM is redirected to the CONTRAST pin of your LCD connector.		Backlight control is done through the i.MX integrated backlight PWM (inside LCDC module). The output signal of this PWM is redirected to the CONTRAST pin of your LCD connector.

	In short the driver is mainly exporting a ''/sys'' interface to user space, allowing you to change the Duty Cycle of the PWM output signal and so the backlight intensity of the LCD.		In short the driver is mainly exporting a ''/sys'' interface to user space, allowing you to change the Duty Cycle of the PWM output signal and so the backlight intensity of the LCD.

JulienB: /* Usage */

2009-09-15T11:45:54Z

Usage

← Older revision		Revision as of 13:45, 15 September 2009
Line 38:		Line 38:
	</pre>		</pre>

	There is a small test script in ''target/linux/modules/backlight/test/''		===Examples===
			* There is a small test script (shell) in ''target/linux/modules/backlight/test/''
			* For a C/[[SDL]] example, take a look at ''target/demos/backlight_control/''

	==Links==		==Links==

JulienB: install by default

2009-03-08T13:58:49Z

install by default

@@ Line 8: / Line 8: @@
 ==Installation==
-This driver is now installed by default on the standard Armadeus rootfs. So, following instructions are only given as reference.
+This driver is now installed by default on the standard Armadeus rootfs.
 ==Usage==

JulienB: apf27 compatible now

2009-02-06T09:10:43Z

apf27 compatible now

← Older revision		Revision as of 11:10, 6 February 2009
Line 34:		Line 34:
	All backlight controls are done through the ''/sys'' interface:		All backlight controls are done through the ''/sys'' interface:
	<pre class="apf">		<pre class="apf">
	# ls /sys/class/backlight/~~imxl~~-bl/		# ls /sys/class/backlight/imx-bl/
	actual_brightness max_brightness subsystem		actual_brightness max_brightness subsystem
	brightness power uevent		brightness power uevent
Line 41:		Line 41:
	* To see the actual brightness:		* To see the actual brightness:
	<pre class="apf">		<pre class="apf">
	# cat /sys/class/backlight/~~imxl~~-bl/actual_brightness		# cat /sys/class/backlight/imx-bl/actual_brightness
	</pre>		</pre>
	* To see the max allowed brightness:		* To see the max allowed brightness:
	<pre class="apf">		<pre class="apf">
	# cat /sys/class/backlight/~~imxl~~-bl/max_brightness		# cat /sys/class/backlight/imx-bl/max_brightness
	</pre>		</pre>
	* To change the brightness:		* To change the brightness:
	<pre class="apf">		<pre class="apf">
	# echo 100 > /sys/class/backlight/~~imxl~~-bl/brightness		# echo 100 > /sys/class/backlight/imx-bl/brightness
	</pre>		</pre>

JulienB: /* Installation */

2009-02-06T09:09:43Z

Installation

← Older revision		Revision as of 11:09, 6 February 2009
Line 12:		Line 12:
	$ make linux26-menuconfig		$ make linux26-menuconfig
	</pre>		</pre>
			<pre class="config">
	* in '''Device Drivers ---> Graphics support ---> Backlight & LCD device support~~''', select '''~~<M> Lowlevel Backlight controls~~'''~~		Device Drivers --->
	* in '''Device Drivers ---> Armadeus specific drivers ---> Support for specific Armadeus drivers~~''', select '''~~<M> i.MX backlight driver~~'''~~		Graphics support --->
			Backlight & LCD device support
			<M> Lowlevel Backlight controls
			...
			Armadeus specific drivers --->
			Support for specific Armadeus drivers
			<M> i.MX backlight driver
			</pre>
	* If built in kernel, reflash your kernel image; if selected as module either reflash your rootfs or copy ''backlight.ko'', ''imx_bl.ko'' and ''.../lib/modules/2.6.18.1/modules.dep'' to your target (for more infos: [[Linux_drivers_generalities]]).		* If built in kernel, reflash your kernel image; if selected as module either reflash your rootfs or copy ''backlight.ko'', ''imx_bl.ko'' and ''.../lib/modules/2.6.18.1/modules.dep'' to your target (for more infos: [[Linux_drivers_generalities]]).

FabienM at 17:07, 5 February 2009

2009-02-05T17:07:25Z

← Older revision		Revision as of 19:07, 5 February 2009
Line 2:		Line 2:

	==Introduction==		==Introduction==
	Backlight control is done through the i.MXL/i.MX27 integrated backlight PWM (inside LCDC module). The output signal of this PWM is redirected to the CONTRAST pin of your LCD connector.~~<br>~~
			Backlight control is done through the i.MXL/i.MX27 integrated backlight PWM (inside LCDC module). The output signal of this PWM is redirected to the CONTRAST pin of your LCD connector.

	In short the driver is mainly exporting a ''/sys'' interface to user space, allowing you to change the Duty Cycle of the PWM output signal and so the backlight intensity of the LCD.		In short the driver is mainly exporting a ''/sys'' interface to user space, allowing you to change the Duty Cycle of the PWM output signal and so the backlight intensity of the LCD.

	==Installation==		==Installation==
	This driver is now installed by default on the standard Armadeus rootfs. So, following instructions are only given as reference.		This driver is now installed by default on the standard Armadeus rootfs. So, following instructions are only given as reference.
			<pre class="host">
	$ make linux26-menuconfig		$ make linux26-menuconfig
			</pre>

	* in '''Device Drivers ---> Graphics support ---> Backlight & LCD device support''', select '''<M> Lowlevel Backlight controls'''		* in '''Device Drivers ---> Graphics support ---> Backlight & LCD device support''', select '''<M> Lowlevel Backlight controls'''
	* in '''Device Drivers ---> Armadeus specific drivers ---> Support for specific Armadeus drivers''', select '''<M> i.MX backlight driver'''		* in '''Device Drivers ---> Armadeus specific drivers ---> Support for specific Armadeus drivers''', select '''<M> i.MX backlight driver'''
Line 13:		Line 18:

	==Usage==		==Usage==

	On your APF, load the module:		On your APF, load the module:
			<pre class="apf">
	# modprobe imx_bl		# modprobe imx_bl
	i.MX Backlight driver v0.X initialized.		i.MX Backlight driver v0.X initialized.
			</pre>

	All backlight controls are done through the ''/sys'' interface:		All backlight controls are done through the ''/sys'' interface:
			<pre class="apf">
	# ls /sys/class/backlight/imxl-bl/		# ls /sys/class/backlight/imxl-bl/

	actual_brightness max_brightness subsystem		actual_brightness max_brightness subsystem
	brightness power uevent		brightness power uevent
			</pre>

	* To see the actual brightness:		* To see the actual brightness:
			<pre class="apf">
	# cat /sys/class/backlight/imxl-bl/actual_brightness		# cat /sys/class/backlight/imxl-bl/actual_brightness
			</pre>
	* To see the max allowed brightness:		* To see the max allowed brightness:
			<pre class="apf">
	# cat /sys/class/backlight/imxl-bl/max_brightness		# cat /sys/class/backlight/imxl-bl/max_brightness
			</pre>
	* To change the brightness:		* To change the brightness:
			<pre class="apf">
	# echo 100 > /sys/class/backlight/imxl-bl/brightness		# echo 100 > /sys/class/backlight/imxl-bl/brightness
			</pre>

	There is a small test script in ''target/linux/modules/backlight/test/''		There is a small test script in ''target/linux/modules/backlight/test/''

	==Links==		==Links==

	* [http://en.wikipedia.org/wiki/Pulse-width_modulation#Power_delivery How a PWM is working]		* [http://en.wikipedia.org/wiki/Pulse-width_modulation#Power_delivery How a PWM is working]
	* http://www.armadeus.com/wiki/index.php?title=FrameBuffer#Tips		* http://www.armadeus.com/wiki/index.php?title=FrameBuffer#Tips

	[[Category:Linux drivers]]		[[Category:Linux drivers]]