DavidVTaylor
Posts: 7
Joined: Mon Oct 12, 2015 5:16 pm

Re: Sleep Mode - and or turn off backlight?

Mon Nov 02, 2015 3:10 pm

Has anyone tested the firmware commit made over the weekend on 11/1?

firmware: rpi_display: fix backlight ratelimiting on STC rollover

JimmyN
Posts: 1109
Joined: Wed Mar 18, 2015 7:05 pm
Location: Virginia, USA

Re: Sleep Mode - and or turn off backlight?

Mon Nov 02, 2015 3:14 pm

I didn't know anything about it, but I'll image my SD card first, and then give it a try.

DirkS
Posts: 7409
Joined: Tue Jun 19, 2012 9:46 pm
Location: Essex, UK

Re: Sleep Mode - and or turn off backlight?

Mon Nov 02, 2015 3:22 pm

DavidVTaylor wrote:Has anyone tested the firmware commit made over the weekend on 11/1?

firmware: rpi_display: fix backlight ratelimiting on STC rollover
Apparently not completely solved; check out https://github.com/raspberrypi/linux/issues/1179

JimmyN
Posts: 1109
Joined: Wed Mar 18, 2015 7:05 pm
Location: Virginia, USA

Re: Sleep Mode - and or turn off backlight?

Mon Nov 02, 2015 3:29 pm

Yes, I was just reading that while waiting to image my SDcard. Looks like it's still a no-go, but at least I just made a current backup of my SDcard.

jdb
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 1677
Joined: Thu Jul 11, 2013 2:37 pm

Re: Sleep Mode - and or turn off backlight?

Mon Nov 02, 2015 8:13 pm

Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.
Rockets are loud.
https://astro-pi.org

lichtteil
Posts: 2
Joined: Mon Sep 21, 2015 6:52 pm

Re: Sleep Mode - and or turn off backlight?

Tue Nov 03, 2015 8:39 am

jdb wrote:Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.
That would be really disappointing :cry:
Any idea how to find a "hacky" way to accomplish it? Is the PI to display communication not the same like switching bl on and off?

Aramas
Posts: 16
Joined: Tue Sep 29, 2015 10:24 am
Location: France - Lille

Re: Sleep Mode - and or turn off backlight?

Wed Nov 04, 2015 7:57 am

Hello all,

Here is some feedback for me : it's two days that i'm with the latest firmware ( 11/01 ) and everything looks fine.
After one night of screen off, there were no problem to bring it on.

And still the update, my screen had zero freeze. I don't know if it's luck or the firmware.

Thanks for the work !

fruit-uk
Posts: 609
Joined: Wed Aug 06, 2014 4:19 pm
Location: Suffolk, UK

Re: Sleep Mode - and or turn off backlight?

Wed Nov 04, 2015 8:22 am

lichtteil wrote:
jdb wrote:Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.
That would be really disappointing :cry:
Any idea how to find a "hacky" way to accomplish it? Is the PI to display communication not the same like switching bl on and off?
Can the display characteristics be altered in the same way as a monitor (through the window manager, not display hard/firmware) - brightness, contrast, gamma etc.?
Mine is elsewhere so I can't try but it might be worth exploring

Mark_T
Posts: 149
Joined: Sat Dec 27, 2014 10:54 am

Re: Sleep Mode - and or turn off backlight?

Wed Nov 04, 2015 12:38 pm

I suspect the limitation on brightness support is an EMI issue?

edje9
Posts: 6
Joined: Wed Nov 04, 2015 3:02 pm

Re: Sleep Mode - and or turn off backlight?

Wed Nov 04, 2015 3:06 pm

jdb wrote:Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.
I hope that this statement is for the current release, and not final.
Will there be an update to enable the variable brightness control?

dobova86
Posts: 53
Joined: Wed Dec 05, 2012 5:32 pm

Re: Sleep Mode - and or turn off backlight?

Wed Nov 04, 2015 6:08 pm

I'm also running last 4.1.12 firmware and it works now, no problem with backlight.

cpfeil
Posts: 15
Joined: Wed Dec 25, 2013 1:35 pm

Re: Sleep Mode - and or turn off backlight?

Thu Nov 05, 2015 8:42 am

Hi,

I have also installed the latest firmware update on my pi.

No more problems turning the display on/off or "waking up" after a couple of hours just by touching it.

Best regards,
Christian

GekkePrutser
Posts: 36
Joined: Sat Mar 23, 2013 5:09 pm

Re: Sleep Mode - and or turn off backlight?

Fri Nov 06, 2015 11:35 am

The lack of brightness adjustment is really disappointing. I don't understand why it's not possible, as there is a PWM controller on the display according to Gordon's comments?

I could imagine it interferes with the touch controller but then it'd still be great to have it for applications where touch is not needed.

chris22
Posts: 2
Joined: Sun Nov 11, 2012 5:47 pm

Re: Sleep Mode - and or turn off backlight?

Fri Nov 06, 2015 8:07 pm

The current lack of support for brightness control is more than disappointing , From the previous posts I understood that the feature was on its way. I was just about to commit to a pcb implementation which includes an ambient light sensor to provide the control signal via the I2C bus.
I am using the display as part of data monitoring system within a car. This means that if the display is bright enough for daylight use then it will be far too bright for night time running so this application needs brightness control.

Looking forward to ideas on work arounds for this missing feature, may be the short terms solution is sun glasses for the display?

GekkePrutser
Posts: 36
Joined: Sat Mar 23, 2013 5:09 pm

Re: Sleep Mode - and or turn off backlight?

Fri Nov 06, 2015 9:46 pm

Yeah a gel filter foil should do the job in the mean time. I wanted to make a cool alarm clock with the option of looking at live view of the raspberry cams I have. But it'd take away from the colour fidelity and contrast (which isn't that great to begin with).

There must be some way to talk to the PWM controller. By the way here is the post from Gordon where he speaks about the Atmel controlling the backlight, and that it can do PWM. The big problem with someone from outside the foundation making a driver, is that it's embedded in the GPU code and that's not open source due to Broadcom's NDA.

If it's really an EMI issue, like Mark_T was speculating above, maybe it would be possible to unofficially 'leak' the code to make it possible ;) As the display would only be tested with its official drivers anyway. I'm sure my raspberry pi cams with extended 2 metre ribbon cables don't meet the EMI specs anymore either. If it's modified by the user in an unsanctioned mod then the foundation is not responsible. I know this is a bit unorthodox but it is a maker's part after all - not a finished product.

tvoverbeek
Posts: 89
Joined: Mon Feb 04, 2013 9:50 am
Location: Fieberbrunn, Austria

Re: Sleep Mode - and or turn off backlight?

Sat Nov 14, 2015 5:58 pm

Note that in a recent github commit (https://github.com/raspberrypi/linux/co ... 75d7337efc) there is a new driver for the RPi 7 insch display backlight.
If I understand the code correctly, it will only be possible to switch the backlight on and off, no brightness control.
Please correct me if I am wrong.
The linux code uses the mailbox interface to the GPU.
An updated GPU firmware is needed to understand the mailbox messages.
So I expect this to show up in the next formal raspbian release.

Marques de Monsas
Posts: 11
Joined: Tue Sep 29, 2015 4:34 pm

Re: Sleep Mode - and or turn off backlight?

Sun Nov 15, 2015 11:56 pm

Please clarify. Is backlight adjustment possible in future or not? If not, why not?

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kusti8
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Location: USA

Re: Sleep Mode - and or turn off backlight?

Sun Nov 15, 2015 11:59 pm

Marques de Monsas wrote:Please clarify. Is backlight adjustment possible in future or not? If not, why not?
In the future, probably. GPU support is needed, which only the Foundation can do since they access, so you'll just have to wait.
There are 10 types of people: those who understand binary and those who don't.

Marques de Monsas
Posts: 11
Joined: Tue Sep 29, 2015 4:34 pm

Re: Sleep Mode - and or turn off backlight?

Mon Nov 16, 2015 8:36 pm

kusti8 wrote:
Marques de Monsas wrote:Please clarify. Is backlight adjustment possible in future or not? If not, why not?
In the future, probably. GPU support is needed, which only the Foundation can do since they access, so you'll just have to wait.
Thank you for you reply, but I was hopping some one from the foundation or some one with real knowledge to respond and confirm this, as there has been mixed views over this lately. Some rumours are stating that the backlight adjustment is not possible. I would like to know if this really is the case, so we can move our efforts to some other hardware where this simple thing is possible and don't waste our time with raspberrys.

FYI: I have read the whole thread and most parts of the dev threads linked in this one.

JimmyN
Posts: 1109
Joined: Wed Mar 18, 2015 7:05 pm
Location: Virginia, USA

Re: Sleep Mode - and or turn off backlight?

Mon Nov 16, 2015 8:46 pm

Marques de Monsas wrote: Thank you for you reply, but I was hopping some one from the foundation or some one with real knowledge to respond and confirm this, as there has been mixed views over this lately.

FYI: I have read the whole thread and most parts of the dev threads linked in this one.
You must have missed this one, it's about a dozen posts up.
jdb wrote:Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.

lapoltba
Posts: 46
Joined: Wed Aug 29, 2012 11:06 am

Re: Sleep Mode - and or turn off backlight?

Tue Nov 17, 2015 7:32 pm

This is really disappointing to hear. I would think that having backlight control (dimming and on/off) would be on the list of requirements for something like this. I'm not sure if it was an oversight or a conscious choice, but now that I have a $60 LCD screen that I can't dim I'm not all that happy about my purchase.

I hope this isn't the final word on the issue and work is still being done on implementing backlight control other than just on/off.

Marques de Monsas
Posts: 11
Joined: Tue Sep 29, 2015 4:34 pm

Re: Sleep Mode - and or turn off backlight?

Tue Nov 17, 2015 10:28 pm

You must have missed this one, it's about a dozen posts up.
jdb wrote:Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.
No I have not. Still missing the reason why not... If it is EMI, then there might be a hack or work around. I don't understand why they are withholding the information? As of now the display seems more and more a flop and almost useless peace of hardware.
This whole display thing could have been handled way better. I sincerely hope that they have at least learnt from their mistakes.

ulix
Posts: 72
Joined: Sat Apr 14, 2012 6:11 pm

Re: Sleep Mode - and or turn off backlight?

Wed Nov 18, 2015 5:41 pm

Marques de Monsas wrote:You must have missed this one, it's about a dozen posts up.
jdb wrote:Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible.
No I have not. Still missing the reason why not... If it is EMI, then there might be a hack or work around. I don't understand why they are withholding the information? As of now the display seems more and more a flop and almost useless peace of hardware.
This whole display thing could have been handled way better. I sincerely hope that they have at least learnt from their mistakes.
+1

I like the display, but with this tweaks worthless!

Snyder
Posts: 31
Joined: Fri Sep 04, 2015 9:25 am

Re: Sleep Mode - and or turn off backlight?

Mon Nov 23, 2015 9:46 am

Hi all,

I have installed the latest firmware with:

Code: Select all

sudo apt-get install rpi-update 
sudo rpi-update
Then I tried to switch on/off the DSI Display using:

Code: Select all

echo 0 > /sys/class/backlight/rpi_backlight/bl_power
echo 1 > /sys/class/backlight/rpi_backlight/bl_power
I got the same error as described by Andrew earlier in this thread: Permission denied
I also tried to execute the above mentioned code with sudo but it didn´t help.

The permission error could be fixed by giving all users the backlight controll permissions:

Code: Select all

sudo nano /etc/udev/rules.d/backlight-permissions.rules
In this file I added the follwing line:

Code: Select all

SUBSYSTEM=="backlight",RUN+="/bin/chmod 666 /sys/class/backlight/rpi_backlight/brightness /sys/class/backlight/rpi_backlight/bl_power"
After rebooting my pi I was able to control the backlight. :D

Now I can turn it on/off a couple of times until the pi crashes and starts rebooting for some reason that I don´t know. :shock:

I wonder why the pi reboots sometimes and sometimes not while trying to turn on/off the backlight?

Can anybody help?

Many thanks in advance, Martin

cpfeil
Posts: 15
Joined: Wed Dec 25, 2013 1:35 pm

Re: Sleep Mode - and or turn off backlight?

Mon Nov 23, 2015 2:54 pm

Hi,

I'am running my raspberry pi and the official touchscreen for over 7 days / 24h now.

I use a small motion sensor to control the backlight.
It works fine so far, no problems at all!

The only thing I noticed: The display does not know it's status (if it is on or off) sometimes.
Before I was asking for the status of the display (on/off) before executing the commands for switching it on or off.

Is you pi rebooting also without the connected display? Have you tried it?
Maye a problem with your power source?

Best regards,
Christian

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