Device Overlay to Disable USR0 LED

[joshuap...@gmail.com]

HI Forum,

I am attempting to create a device over lay for BBB "Linux beaglebone 3.8.13-bone70" that will disable the linux heartbeat LED.  

I am interested to do this primary as a learning process for device tree, but I plan to use the BBB in a room where I don't want a LED to flash.

I followed the guide at http://elinux.org/BeagleBone_and_the_3.8_Kernel. 

dtc -O dtb -o BBB-LEDS.dtbo -b 0 -@ BBB-LEDS-00A0.dts

sudo cp BBB-LEDS.dtbo /lib/firmware/

sudo sh -c "echo BBB-LEDS > /sys/devices/bone_capemgr.9/slots"

However the LED continues to flash.

Could someone point me how to get the overlay to work?

Thanks

Joshua

/dts-v1/;

/plugin/;

/

{

 compatible = "ti,beaglebone", "ti,beaglebone-black";

 part-number = "BBB-LEDS";

 version = "00A0";

 fragment@0

 {

   target = <&am33xx_pinmux>;

    __overlay__ 

   {

 userled_pins: pinmux_userled_pins {

pinctrl-single,pins = <

0x54 0x7 /* gpmc_a5.gpio1_21, OUTPUT | MODE7 */

>;

 };

    };

 };

 fragment@1

  {

     target = <&ocp>;

     __overlay__

     {

         gpio-leds {

             compatible = "gpio-leds";

             pinctrl-names = "default";

             pinctrl-0 = <&userled_pins>;

             led0 {

                 label = "beaglebone:green:usr0";

                 gpios = <&gpio2 21 0>;

                 linux,default-trigger = "none";

                 default-state = "off";

             };

         };

     };

   };

};

[Robert Nelson]

On Wed, Jun 10, 2015 at 7:03 AM, <joshuap...@gmail.com> wrote:
> HI Forum,
>
> I am attempting to create a device over lay for BBB "Linux beaglebone
> 3.8.13-bone70" that will disable the linux heartbeat LED.
>
> I am interested to do this primary as a learning process for device tree,
> but I plan to use the BBB in a room where I don't want a LED to flash.
>
> I followed the guide at http://elinux.org/BeagleBone_and_the_3.8_Kernel.
>
> dtc -O dtb -o BBB-LEDS.dtbo -b 0 -@ BBB-LEDS-00A0.dts
>
> sudo cp BBB-LEDS.dtbo /lib/firmware/
>
> sudo sh -c "echo BBB-LEDS > /sys/devices/bone_capemgr.9/slots"
>
>
> However the LED continues to flash.
>
> Could someone point me how to get the overlay to work?

Just shut them down via a script from userspace:

BASE=/sys/class/leds/beaglebone\:green\:usr

echo none > ${BASE}0/trigger
echo none > ${BASE}1/trigger
echo none > ${BASE}2/trigger
echo none > ${BASE}3/trigger

echo 0 > ${BASE}0/brightness
echo 0 > ${BASE}1/brightness
echo 0 > ${BASE}2/brightness
echo 0 > ${BASE}3/brightness

Regards,

--
Robert Nelson
https://rcn-ee.com/

[735...@gmail.com]

Hello Joshua, 

Not sure if you'll see this but here goes.

You can modify the base dtb file at /boot/dtbs/3.8.XX-boneXX/am335x-boneblack.dtb by converting to dts, modifying, and converting back.  I followed the guide here, specifically "What is the device tree?" and step 1:http://www.element14.com/community/community/designcenter/single-board-computers/next-gen_beaglebone/blog/2013/05/22/bbb--working-with-the-pru-icssprussv2

cd /boot/dtbs/3.8.13-bone70/ # navigate to dtb directory, may have to change version numbers
cp am335x-boneblack.dtb am335x-boneblack.dtb_orig # create a backup of the dtb incase anything goes wrong
dtc -I dtb -O dts am335x-boneblack.dtb > am335x-boneblack.dts_noled # convert dtb file to dts (human readable)
nano am335x-boneblack.dts_noled # open the file for editing with your favorite editor

Search for "led0".  Should be line no. ~946

 946                         led0 {

 947                                 label = "beaglebone:green:usr0";

 948                                 gpios = <0x5 0x15 0x0>;

 949                                 linux,default-trigger = "heartbeat";

 950                                 default-state = "off";

 951                         };

 952

 953                         led1 {

 954                                 label = "beaglebone:green:usr1";

 955                                 gpios = <0x5 0x16 0x0>;

 956                                 linux,default-trigger = "mmc0";

 957                                 default-state = "off";

 958                         };

 959

 960                         led2 {

 961                                 label = "beaglebone:green:usr2";

 962                                 gpios = <0x5 0x17 0x0>;

 963                                 linux,default-trigger = "cpu0";

 964                                 default-state = "off";

 965                         };

 966

 967                         led3 {

 968                                 label = "beaglebone:green:usr3";

 969                                 gpios = <0x5 0x18 0x0>;

 970                                 default-state = "off";

 971                                 linux,default-trigger = "mmc1";

 972                         };

All you have to do is change this line in led0

linux,default-trigger = "heartbeat";

to

linux,default-trigger = "none";

You can also repeat for leds 1,2, and 3 if desired.

Now just convert the dts back to dtb:

dtc -I dts -O dtb am335x-boneblack.dts_noled > am335x-boneblack.dtb_noled
cp am335x-boneblack.dtb_noled am335x-boneblack.dtb

and reboot!  Your leds should now be disabled.

If anything goes wrong you can always start over with your original backup copy.