Nont able to use overlay at boot time

[Mrigendra Chaubey]

Hi All,

I face this problem of not being able to make overlay work at boot time.I checked these threads,

https://stackoverflow.com/questions/17768714/bbb-automatically-load-a-device-tree-overlay-on-boot

https://groups.google.com/forum/#!msg/beagleboard/jYpYHZPl1ig/90BPMxxhWLMJ

 and I added optargs=capemgr.enable_partno=BB-I2C2-ADXL in uEnv.txt

This is my uboot version 

U-Boot 2017.09-dirty (Oct 14 2017 - 21:00:59 +0530)

I am booting with this kernl image

vmlinuz-4.4.92-bone-rt-r19

and I am trying to add an overlay at boot time for adxl345.

1)go to /boot/uEnv.txt add following two lines

root@arm:~# cat /boot/uEnv.txt

uname_r=4.4.92-bone-rt-r19

cmdline=coherent_pool=1M quiet cape_universal=enable optargs=capemgr.enable_partno=BB-I2C2-ADXL

I compiled overlay file(BB-I2C2-ADXL-00A0.dts) and put it into lib/firmware

BB-I2C2-ADXL-00A0.dtbo 

Standalone this works

echo "BB-I2C2-ADXL" > slots 

I can see my driver probing it.

But adding this functionality in eEnv.txt does not take effect.

Overlay file

https://pastebin.com/raw/T3bZKyT8

This is my kernel log while boot up,

 

https://pastebin.com/raw/EmiAedQz

this is dmesg

https://pastebin.com/raw/6PVVBHeD

What I am missing?

[Robert Nelson]

Just use u-boot overlays:

https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Overlays

in /boot/uEnv.txt:

enable_uboot_overlays=1
uboot_overlay_addr0=/lib/firmware/BB-I2C2-ADXL-00A0.dtbo

Regards,

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

[Mrigendra Chaubey]

That works.

I removed other entried in uEnv.txt and changed it to 

enable_uboot_overlays=1
uboot_overlay_addr0=/lib/firmware/BB-I2C2-ADXL-00A0.dtbo

Now I can see my driver probing.

One thing happened. I tried to see slots

cat /sys/device/platform/bone.capemgr/slots

cat: slots: No such file or directory

slots file itself is not present now.

[Robert Nelson]

On Nov 7, 2017 10:49 PM, "Mrigendra Chaubey" <mrigendr...@gmail.com> wrote:

That works.

I removed other entried in uEnv.txt and changed it to 

enable_uboot_overlays=1
uboot_overlay_addr0=/lib/firmware/BB-I2C2-ADXL-00A0.dtbo

Now I can see my driver probing.

One thing happened. I tried to see slots

cat /sys/device/platform/bone.capemgr/slots

cat: slots: No such file or directory

slots file itself is not present now.

Correct, when using U-Boot overlays, the slots file is removed, as it'll only cause issues. Aka, don't mix and match uboot and kernel overlays.

Regards,

[Mrigendra Chaubey]

Thanks for the clarification.

One suggestion I need. 

What is the best way to keep up with these changes, because these information is so volatile that it may be redundant in few weeks.

Should I go with the source of overlay files and understand from the implementation point of view rather than trying to just make it work somehow.

Which source files or functions would be best to start?

I just need a direction from where I can start.

[Robert Nelson]

On Wed, Nov 8, 2017 at 12:06 AM, Mrigendra Chaubey
<mrigendr...@gmail.com> wrote:
> Thanks for the clarification.
>
> One suggestion I need.
> What is the best way to keep up with these changes, because these
> information is so volatile that it may be redundant in few weeks.
> Should I go with the source of overlay files and understand from the
> implementation point of view rather than trying to just make it work
> somehow.
> Which source files or functions would be best to start?
> I just need a direction from where I can start.

Well the decision was made back in March of 2017 to completely scrap
kernel overlays and move to u-boot overlays.

An announcement was made to this mailing list.