2015-04-16 09:32:43

by Pavel Machek

[permalink] [raw]
Subject: n900 in 4.1-rc0

Hi!

Just tried booting 4.1-rc0 on n900 (commit
34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085) and it is broken.

Any ideas?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


2015-04-16 09:38:04

by Marc Zyngier

[permalink] [raw]
Subject: Re: n900 in 4.1-rc0

On 16/04/15 10:32, Pavel Machek wrote:
> Hi!
>
> Just tried booting 4.1-rc0 on n900 (commit
> 34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085) and it is broken.
>
> Any ideas?

To such a question, the only answer I have is "Yes".

For a more useful reply, I'm afraid you'll have to ask a better question.

Thanks,

M.
--
Jazz is not dead. It just smells funny...

2015-04-16 16:39:19

by Tony Lindgren

[permalink] [raw]
Subject: Re: n900 in 4.1-rc0

* Marc Zyngier <[email protected]> [150416 02:38]:
> On 16/04/15 10:32, Pavel Machek wrote:
> > Hi!
> >
> > Just tried booting 4.1-rc0 on n900 (commit
> > 34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085) and it is broken.
> >
> > Any ideas?
>
> To such a question, the only answer I have is "Yes".
>
> For a more useful reply, I'm afraid you'll have to ask a better question.

Just tried it at 34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085
and it boots just fine on my n900.

Regards,

Tony

2015-04-16 16:45:21

by Tyler Baker

[permalink] [raw]
Subject: Re: n900 in 4.1-rc0

On 16 April 2015 at 02:32, Pavel Machek <[email protected]> wrote:
> Hi!
>
> Just tried booting 4.1-rc0 on n900 (commit
> 34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085) and it is broken.
>
> Any ideas?

Looks like DT and legacy booting are working fine in our labs. [0][1]

> Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
>
> _______________________________________________
> linux-arm-kernel mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Tyler

[0] http://kernelci.org/boot/omap3-n900/
[1] http://kernelci.org/boot/omap3-n900,legacy/

2015-04-26 10:15:28

by Pavel Machek

[permalink] [raw]
Subject: Re: n900 in 4.1-rc0

On Thu 2015-04-16 09:35:54, Tony Lindgren wrote:
> * Marc Zyngier <[email protected]> [150416 02:38]:
> > On 16/04/15 10:32, Pavel Machek wrote:
> > > Hi!
> > >
> > > Just tried booting 4.1-rc0 on n900 (commit
> > > 34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085) and it is broken.
> > >
> > > Any ideas?
> >
> > To such a question, the only answer I have is "Yes".
> >
> > For a more useful reply, I'm afraid you'll have to ask a better question.
>
> Just tried it at 34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085
> and it boots just fine on my n900.

Thanks for testing. I did some investigation, and found that twl4030
charger (that is not useful on n900) was breaking my boot. (And it may
be interaction with some of my local changes).

Best regards (and sorry for the noise),
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-04-26 10:20:50

by Pavel Machek

[permalink] [raw]
Subject: Re: n900 in 4.1-rc0

Hi!

> > Just tried booting 4.1-rc0 on n900 (commit
> > 34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085) and it is broken.
> >
> > Any ideas?
>
> Looks like DT and legacy booting are working fine in our
> labs. [0][1]

Interesting web pages, thanks.

I noticed that legacy booting indicates broken today, but... Is there
list of your targets somewhere?

Best regards,
Pavel



> [0] http://kernelci.org/boot/omap3-n900/
> [1] http://kernelci.org/boot/omap3-n900,legacy/

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-04-27 18:58:10

by Tyler Baker

[permalink] [raw]
Subject: Re: n900 in 4.1-rc0

Hi Pavel,

On 26 April 2015 at 03:20, Pavel Machek <[email protected]> wrote:
> Hi!
>
>> > Just tried booting 4.1-rc0 on n900 (commit
>> > 34c9a0ffc75ad25b6a60f61e27c4a4b1189b8085) and it is broken.
>> >
>> > Any ideas?
>>
>> Looks like DT and legacy booting are working fine in our
>> labs. [0][1]
>
> Interesting web pages, thanks.

No problem.

>
> I noticed that legacy booting indicates broken today, but... Is there
> list of your targets somewhere?

It looks to have failed it's boot test on the stable v3.14 based LSK
today, however it is booting fine still on the upstream development
trees. You can also use a query[0] to refine your view if you would
like. The up to date list of targets can be found here[1] and if
interested in receiving email reports you can subscribe here[2].

>
> Best regards,
> Pavel
>
>
>
>> [0] http://kernelci.org/boot/omap3-n900/
>> [1] http://kernelci.org/boot/omap3-n900,legacy/
>
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Cheers,

Tyler

[0] http://kernelci.org/boot/?n900&fail
[1] https://wiki.linaro.org/ProductTechnology/kernelci.org
[2] https://lists.linaro.org/mailman/listinfo/kernel-build-reports

2015-06-29 09:11:56

by Pavel Machek

[permalink] [raw]
Subject: n900 in 4.2-rc0: repeating oopses

Hi!

Just tried booting 4.2-rc0 on n900 (commit
4a10a91756ef381bced7b88cfb9232f660b92d93) and it is broken. Previous
-rc0 version worked. This time, there's some output on console, but
too fast for me to read.

It seems oopses happen before mounting root. If you have serial
console, they should be easy to see.

I tried booting same kernel in qemu, but it seems to work ok there.

Any ideas? Thanks,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-06-29 10:46:54

by Pali Rohár

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

Hi!

On Monday 29 June 2015 11:11:46 Pavel Machek wrote:
> Hi!
>
> Just tried booting 4.2-rc0 on n900 (commit
> 4a10a91756ef381bced7b88cfb9232f660b92d93) and it is broken. Previous
> -rc0 version worked. This time, there's some output on console, but
> too fast for me to read.
>

What happen after errors are reported? Maybe you can enable R&D mode and
disable HW watchdogs to prevent device reboots...

> It seems oopses happen before mounting root. If you have serial
> console, they should be easy to see.
>
> I tried booting same kernel in qemu, but it seems to work ok there.
>

Hm... Maybe problem with HS code?

By chance, can you try to disable (omap) sham node in n900 DT file?
(same way like omap aes is disabled)

> Any ideas? Thanks,
> Pavel

--
Pali Rohár
[email protected]

2015-06-30 09:24:15

by Pavel Machek

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

Hi!

> Just tried booting 4.2-rc0 on n900 (commit
> 4a10a91756ef381bced7b88cfb9232f660b92d93) and it is broken. Previous
> -rc0 version worked. This time, there's some output on console, but
> too fast for me to read.
>
> It seems oopses happen before mounting root. If you have serial
> console, they should be easy to see.

I tried again according to pali's instructions, and it is still
broken the same way. Any other ideas? Does it work for you?

diff --git a/arch/arm/boot/dts/omap3.dtsi b/arch/arm/boot/dts/omap3.dtsi
index 69a40cf..ff6f2bf 100644
--- a/arch/arm/boot/dts/omap3.dtsi
+++ b/arch/arm/boot/dts/omap3.dtsi
@@ -570,6 +570,7 @@
interrupts = <49>;
dmas = <&sdma 69>;
dma-names = "rx";
+ status = "disabled";
};

smartreflex_core: smartreflex@480cb000 {

Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-06-30 09:53:22

by Pali Rohár

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

On Tuesday 30 June 2015 11:24:04 Pavel Machek wrote:
> Hi!
>
> > Just tried booting 4.2-rc0 on n900 (commit
> > 4a10a91756ef381bced7b88cfb9232f660b92d93) and it is broken. Previous
> > -rc0 version worked. This time, there's some output on console, but
> > too fast for me to read.
> >
> > It seems oopses happen before mounting root. If you have serial
> > console, they should be easy to see.
>
> I tried again according to pali's instructions, and it is still
> broken the same way. Any other ideas? Does it work for you?
>
> diff --git a/arch/arm/boot/dts/omap3.dtsi b/arch/arm/boot/dts/omap3.dtsi
> index 69a40cf..ff6f2bf 100644
> --- a/arch/arm/boot/dts/omap3.dtsi
> +++ b/arch/arm/boot/dts/omap3.dtsi
> @@ -570,6 +570,7 @@
> interrupts = <49>;
> dmas = <&sdma 69>;
> dma-names = "rx";
> + status = "disabled";
> };
>
> smartreflex_core: smartreflex@480cb000 {
>
> Pavel
>

Ok, then it is not problem with omap crypto and HS device...

I will try 4.2 at the end of week.

--
Pali Rohár
[email protected]

2015-07-01 06:59:45

by Tony Lindgren

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

* Pali Rohár <[email protected]> [150630 02:55]:
>
> I will try 4.2 at the end of week.

At least today's 4.1.0-11549-g05a8256 boots just fine on my n900.

Regards,

Tony

2015-07-01 07:23:06

by Pali Rohár

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

On Tuesday 30 June 2015 23:59:33 Tony Lindgren wrote:
> * Pali Rohár <[email protected]> [150630 02:55]:
> >
> > I will try 4.2 at the end of week.
>
> At least today's 4.1.0-11549-g05a8256 boots just fine on my n900.
>
> Regards,
>
> Tony

So, Pavel can you re-test? Maybe there can be problem with some driver
which Tony did not compiled into zImage? Just speculation...

--
Pali Rohár
[email protected]

2015-07-01 10:00:05

by Pavel Machek

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

On Wed 2015-07-01 09:22:55, Pali Roh?r wrote:
> On Tuesday 30 June 2015 23:59:33 Tony Lindgren wrote:
> > * Pali Roh?r <[email protected]> [150630 02:55]:
> > >
> > > I will try 4.2 at the end of week.
> >
> > At least today's 4.1.0-11549-g05a8256 boots just fine on my n900.
> >
> > Regards,
> >
> > Tony
>
> So, Pavel can you re-test? Maybe there can be problem with some driver
> which Tony did not compiled into zImage? Just speculation...

I re-tested with today's git, and it seems to boot. Thanks for help...

Now. "echo mem > /sys/power/state" is broken, as in "returns
immediately in about 50% cases". The messages are

Powerdomain (per_pwrdm) didn't enter target state 1
Powerdomain (core_pwerdm) didn't enter target state 1

Any ideas? Thanks,

Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-07-01 10:34:34

by Tony Lindgren

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

* Pavel Machek <[email protected]> [150701 03:02]:
> On Wed 2015-07-01 09:22:55, Pali Rohár wrote:
> > On Tuesday 30 June 2015 23:59:33 Tony Lindgren wrote:
> > > * Pali Rohár <[email protected]> [150630 02:55]:
> > > >
> > > > I will try 4.2 at the end of week.
> > >
> > > At least today's 4.1.0-11549-g05a8256 boots just fine on my n900.
> > >
> > > Regards,
> > >
> > > Tony
> >
> > So, Pavel can you re-test? Maybe there can be problem with some driver
> > which Tony did not compiled into zImage? Just speculation...
>
> I re-tested with today's git, and it seems to boot. Thanks for help...

OK good to hear.

> Now. "echo mem > /sys/power/state" is broken, as in "returns
> immediately in about 50% cases". The messages are
>
> Powerdomain (per_pwrdm) didn't enter target state 1
> Powerdomain (core_pwerdm) didn't enter target state 1
>
> Any ideas? Thanks,

Works for me after enabling the idle timeouts with the following
script and blanking the screen and disconnecting USB:

Also both keyboard LEDs should start blinking after the idle
timeout with screen blanked and USB disconnected. If not, you
have some module loaded that blocks the deeper idle states.

Regrads,

Tony

8< ----
#!/bin/bash

modprobe leds-gpio
modprobe ledtrig-default-on

uarts=$(find /sys/class/tty/ttyO*/device/power/ -type d)
for uart in $uarts; do
echo 3000 > $uart/autosuspend_delay_ms
#echo -1 > $uart/autosuspend_delay_ms
done

uarts=$(find /sys/class/tty/ttyO*/power/ -type d)
for uart in $uarts; do
echo enabled > $uart/wakeup
echo auto > $uart/control
done

echo 255 > /sys/class/backlight/acx565akm/brightness
echo 1 > /sys/devices/platform/omapfb/graphics/fb0/blank

echo 1 > /sys/kernel/debug/pm_debug/enable_off_mode

2015-07-01 13:09:14

by Pavel Machek

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

On Wed 2015-07-01 03:34:22, Tony Lindgren wrote:
> * Pavel Machek <[email protected]> [150701 03:02]:
> > On Wed 2015-07-01 09:22:55, Pali Roh?r wrote:
> > > On Tuesday 30 June 2015 23:59:33 Tony Lindgren wrote:
> > > > * Pali Roh?r <[email protected]> [150630 02:55]:
> > > > >
> > > > > I will try 4.2 at the end of week.
> > > >
> > > > At least today's 4.1.0-11549-g05a8256 boots just fine on my n900.
> > > >
> > > > Regards,
> > > >
> > > > Tony
> > >
> > > So, Pavel can you re-test? Maybe there can be problem with some driver
> > > which Tony did not compiled into zImage? Just speculation...
> >
> > I re-tested with today's git, and it seems to boot. Thanks for help...
>
> OK good to hear.
>
> > Now. "echo mem > /sys/power/state" is broken, as in "returns
> > immediately in about 50% cases". The messages are
> >
> > Powerdomain (per_pwrdm) didn't enter target state 1
> > Powerdomain (core_pwerdm) didn't enter target state 1
> >
> > Any ideas? Thanks,
>
> Works for me after enabling the idle timeouts with the following
> script and blanking the screen and disconnecting USB:

Um. I'm forcing suspend with "echo mem > /sys/power/state" . (It
worked in 4.1). That should just make it sleep, no autosuspend-related
trickery... (But yes, I guess I should set up the leds and try
autosuspend, too.)

Regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-07-02 06:16:33

by Tony Lindgren

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

* Pavel Machek <[email protected]> [150701 06:11]:
> On Wed 2015-07-01 03:34:22, Tony Lindgren wrote:
> >
> > Works for me after enabling the idle timeouts with the following
> > script and blanking the screen and disconnecting USB:
>
> Um. I'm forcing suspend with "echo mem > /sys/power/state" . (It
> worked in 4.1). That should just make it sleep, no autosuspend-related
> trickery... (But yes, I guess I should set up the leds and try
> autosuspend, too.)

That too works just fine for me with omap2plus_defconfig after
echo enabled > /sys/class/tty/ttyO2/power/wakeup as I have n900
in my test rack.

You probably have some additional drivers enabled?

Regards,

Tony

2015-07-02 20:25:42

by Pavel Machek

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

On Wed 2015-07-01 03:34:22, Tony Lindgren wrote:
> * Pavel Machek <[email protected]> [150701 03:02]:
> > On Wed 2015-07-01 09:22:55, Pali Roh?r wrote:
> > > On Tuesday 30 June 2015 23:59:33 Tony Lindgren wrote:
> > > > * Pali Roh?r <[email protected]> [150630 02:55]:
> > > > >
> > > > > I will try 4.2 at the end of week.
> > > >
> > > > At least today's 4.1.0-11549-g05a8256 boots just fine on my n900.
> > > >
> > > > Regards,
> > > >
> > > > Tony
> > >
> > > So, Pavel can you re-test? Maybe there can be problem with some driver
> > > which Tony did not compiled into zImage? Just speculation...
> >
> > I re-tested with today's git, and it seems to boot. Thanks for help...
>
> OK good to hear.

Hmm. Tried to toggle brightness on 4.1, and after few changes:

root@n900:~# echo 255 > /sys/class/backlight/acx565akm/brightness
root@n900:~# echo 120 > /sys/class/backlight/acx565akm/brightness
root@n900:~# echo 10 > /sys/class/backlight/acx565akm/brightness
root@n900:~# echo 1 > /sys/class/backlight/acx565akm/brightness



^C^C
^Z

seems like acx565akm hung :-(.
Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-07-26 09:26:27

by Pavel Machek

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

Hi!

> > > So, Pavel can you re-test? Maybe there can be problem with some driver
> > > which Tony did not compiled into zImage? Just speculation...
> >
> > I re-tested with today's git, and it seems to boot. Thanks for help...
>
> OK good to hear.
>
> > Now. "echo mem > /sys/power/state" is broken, as in "returns
> > immediately in about 50% cases". The messages are
> >
> > Powerdomain (per_pwrdm) didn't enter target state 1
> > Powerdomain (core_pwerdm) didn't enter target state 1
> >
> > Any ideas? Thanks,
>
> Works for me after enabling the idle timeouts with the following
> script and blanking the screen and disconnecting USB:
>
> Also both keyboard LEDs should start blinking after the idle
> timeout with screen blanked and USB disconnected. If not, you
> have some module loaded that blocks the deeper idle states.

Ok, tried that, I had to do:

cd /sys/class/gpio
echo 162 > export
cd gpio162
echo out > direction
echo 1 > value

to get the debug lights to work. But I could not get those leds to
blink.

> modprobe leds-gpio
> modprobe ledtrig-default-on

Is this actually neccessary/relevant?

> echo 255 > /sys/class/backlight/acx565akm/brightness

And this?

Thanks,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-07-26 22:31:23

by Pavel Machek

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

On Wed 2015-07-01 23:16:21, Tony Lindgren wrote:
> * Pavel Machek <[email protected]> [150701 06:11]:
> > On Wed 2015-07-01 03:34:22, Tony Lindgren wrote:
> > >
> > > Works for me after enabling the idle timeouts with the following
> > > script and blanking the screen and disconnecting USB:
> >
> > Um. I'm forcing suspend with "echo mem > /sys/power/state" . (It
> > worked in 4.1). That should just make it sleep, no autosuspend-related
> > trickery... (But yes, I guess I should set up the leds and try
> > autosuspend, too.)
>
> That too works just fine for me with omap2plus_defconfig after
> echo enabled > /sys/class/tty/ttyO2/power/wakeup as I have n900
> in my test rack.

Going through that. AFAICT, you are not using devicetree on n900?

CONFIG_MACH_NOKIA_RX51=y

Unfortunately, not having serials, it is tricky to get any output from
that cnofiguration, so I don't know what I got wrong...
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

2015-07-27 07:12:16

by Pali Rohár

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

On Monday 27 July 2015 00:31:19 Pavel Machek wrote:
> On Wed 2015-07-01 23:16:21, Tony Lindgren wrote:
> > * Pavel Machek <[email protected]> [150701 06:11]:
> > > On Wed 2015-07-01 03:34:22, Tony Lindgren wrote:
> > > >
> > > > Works for me after enabling the idle timeouts with the following
> > > > script and blanking the screen and disconnecting USB:
> > >
> > > Um. I'm forcing suspend with "echo mem > /sys/power/state" . (It
> > > worked in 4.1). That should just make it sleep, no autosuspend-related
> > > trickery... (But yes, I guess I should set up the leds and try
> > > autosuspend, too.)
> >
> > That too works just fine for me with omap2plus_defconfig after
> > echo enabled > /sys/class/tty/ttyO2/power/wakeup as I have n900
> > in my test rack.
>
> Going through that. AFAICT, you are not using devicetree on n900?
>
> CONFIG_MACH_NOKIA_RX51=y
>
> Unfortunately, not having serials, it is tricky to get any output from
> that cnofiguration, so I don't know what I got wrong...
> Pavel

You can try to test it in qemu. It has emulation also of serial.

--
Pali Rohár
[email protected]

2015-07-28 06:01:50

by Tony Lindgren

[permalink] [raw]
Subject: Re: n900 in 4.2-rc0: repeating oopses

* Pavel Machek <[email protected]> [150726 02:29]:
> Hi!
>
> > > > So, Pavel can you re-test? Maybe there can be problem with some driver
> > > > which Tony did not compiled into zImage? Just speculation...
> > >
> > > I re-tested with today's git, and it seems to boot. Thanks for help...
> >
> > OK good to hear.
> >
> > > Now. "echo mem > /sys/power/state" is broken, as in "returns
> > > immediately in about 50% cases". The messages are
> > >
> > > Powerdomain (per_pwrdm) didn't enter target state 1
> > > Powerdomain (core_pwerdm) didn't enter target state 1
> > >
> > > Any ideas? Thanks,
> >
> > Works for me after enabling the idle timeouts with the following
> > script and blanking the screen and disconnecting USB:
> >
> > Also both keyboard LEDs should start blinking after the idle
> > timeout with screen blanked and USB disconnected. If not, you
> > have some module loaded that blocks the deeper idle states.
>
> Ok, tried that, I had to do:
>
> cd /sys/class/gpio
> echo 162 > export
> cd gpio162
> echo out > direction
> echo 1 > value
>
> to get the debug lights to work. But I could not get those leds to
> blink.

I think that's the GPIO override for them? And in that case the
PMIC sys_clkreq and sys_off_mode signals are not cutting off the
LEDs I believe.

Also not that any driver blocking the deeper idle states will
also cause the LEDs to stay on. And USB cable being plugged in
too at least for core off.. So you if you're using NFSroot over
USB Ethernet, you probably can only see the left LED ever go off.

> > modprobe leds-gpio
> > modprobe ledtrig-default-on
>
> Is this actually neccessary/relevant?

Yes at least with omap2plus_defconfig.

> > echo 255 > /sys/class/backlight/acx565akm/brightness
>
> And this?

It used to be the backlight did not come on initially as modules
or something.. May not be needed any longer.

Regards,

Tony