HDMI flickering

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robabruton
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HDMI flickering

Unread post by robabruton » Tue Apr 16, 2019 6:48 pm

Hello,
I received my N2 yesterday and was excited to get it up and running. I'm using an SD card for testing currently (running the MATE desktop Ubuntu image provided on the wiki). I was planning to use this device as a media box eventually, but as of now when it's connected to my TV via HDMI my screen flickers every couple seconds. The device also seems a little unresponsive on the desktop but maybe I was expecting more for this small device. I'm sure Kodi will run fine once it's available for this platform. My issue is that this screen flickering is not going to be okay for use. Is this something that's temporary while the GPU drivers are being developed further or is this something more serious? Could I have done something wrong?

I'm using a quality HDMI cable. I'm running the TV at 4k60. The TV is a common (not obscure model) Samsung LED TV.

Here's a link to a short clip of my flickering issue: https://youtu.be/uYGYw-tFUGE

I'm new to ODROID but excited to learn more. Open to any suggestions or help. Thanks!

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Re: HDMI flickering

Unread post by venkatbo » Tue Apr 16, 2019 10:34 pm

I noticed the same issue on my 4k monitor, while the same works fine with multiple C2's, H2 and Macbook Pro.

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Re: HDMI flickering

Unread post by Gburas » Wed Apr 17, 2019 5:50 am

also have this flickering on a samsung 4k hdr tv

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Re: HDMI flickering

Unread post by odroid » Wed Apr 17, 2019 9:40 am

To narrow down root causes, can you please try other 4K modes after disabling "display_autodetect" option?
https://github.com/mdrjr/n2_bootini/blo ... ni#L24-L31

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Re: HDMI flickering

Unread post by robabruton » Wed Apr 17, 2019 9:56 am

I've tried 4k60 with autodetect disabled and still get this issue (the recording was with autodetect off). I haven't tried any other modes. I'll give them a go and will report back. It may take me a day or so before I get the time to do this though.

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Re: HDMI flickering

Unread post by crashoverride » Wed Apr 17, 2019 4:07 pm

I am sure I have seen this issue before, but I can't find it searching the forum.

Try disabling the X11 compositor:
Control Center / Mate Tweaks / Windows / Window Manager = Marco (No Compositor)
Control Center / Windows / General / Enable Software Compositing Window Manger = No

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Re: HDMI flickering

Unread post by Raybuntu » Thu Apr 18, 2019 12:46 am

Edit: nevermind

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Re: HDMI flickering

Unread post by poincare » Fri Apr 19, 2019 9:43 am

I also get this tearing issue. It appears to happen about every 2-3 minutes. Whether there is mouse movement of if the interface/screen is just idle. I can't seem to get it TO happen; but, I can't seem to prevent it from happening. I am also using a 4K monitor.

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Re: HDMI flickering

Unread post by odroid » Fri Apr 19, 2019 10:28 am

Did you try disabling compositor?

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Re: HDMI flickering

Unread post by joy » Fri Apr 19, 2019 5:01 pm

@robabruton, @poincare,

Do you get this issue all the time, or at specific cases?
We will try to reproduce this issue.

And can you share the following files?

Code: Select all

/media/boot/edid.bin
/media/boot/display.bin
I don't mean it's related to monitor issue, but want to check the pixel clock and timing patterns of your monitors.

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Re: HDMI flickering

Unread post by Gburas » Sat Apr 20, 2019 1:37 am

i have tried disabling compositor and it didn`t help

here are files
https://drive.google.com/drive/folders/ ... sp=sharing

now i will try other hdmi mode

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Re: HDMI flickering

Unread post by Gburas » Sat Apr 20, 2019 2:08 am

on other 4k and 1080p60 screen is still flickering
tv is samsung ue55nu7172u
in a few days i will check with fhd tv screen

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Re: HDMI flickering

Unread post by joy » Mon Apr 22, 2019 10:22 am

@robabruton, @poincare,

Thanks for sharing your status and information.

I've tried it
and now I can reproduce the flickering issue with two of my 4K monitors.

As I checked, I get the problem with 2160p60hz mode only. (3840x2160p60hz)
With 2160p30hz, there's no issue.

Please let me look into into the issue.

When you're available, can you check if you have the issue with "2160p30hz" or "1080p60hz" with your monitors?
It will be very helpful to figure it out.

To set the resolution as "2160p30hz" or "1080p60hz", you need to disable "display_autodetect" and modify "hdmimode" value in boot.ini

Code: Select all

# Auto Detection of Monitor settings based on your Screen information
setenv display_autodetect "false"

Code: Select all

# for 1080p60hz
setenv hdmimode "1080p60hz"

Code: Select all

# for 2160p30hz
setenv hdmimode "2160p30hz"

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Re: HDMI flickering

Unread post by Gburas » Tue Apr 23, 2019 6:29 pm

@joy can You confirm that this problem is on specific 4k monitors, because i have only one 4k tv to test and i want to be sure it`s not fault of my n2 board ?

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Re: HDMI flickering

Unread post by robabruton » Wed Apr 24, 2019 7:48 am

Sorry it has taken me a little while to respond; I'm in the middle of exams at school right now and haven't had much free time. I ordered eMMC memory (running Linux) and out of the box (and after very little testing) I did not have the same flickering issues. I eventually changed my boot settings to what you recommended anyways (2160p30hz, disabled auto detect) and am getting flickering issues again. Not sure what to do. If you need any more info or tests, I'll try to respond back quickly. Thanks for looking into it

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Re: HDMI flickering

Unread post by bugmenot » Thu Apr 25, 2019 6:10 pm

I have to confirm this issue.
when using a LG 4k monitor flickering happens (Flickering can be provoked by activity like opening a terminal or moving the mouse).
using different modes (via boot.ini) did not change behavior (using 30Hz might flicker less frequent)
disabling compositor did not change behavior (via Mate Tweak: Windows - Window manager - select: Macro (No compositor))

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Re: HDMI flickering

Unread post by joy » Mon Apr 29, 2019 12:23 pm

Gburas wrote:
Tue Apr 23, 2019 6:29 pm
@joy can You confirm that this problem is on specific 4k monitors, because i have only one 4k tv to test and i want to be sure it`s not fault of my n2 board ?
@Gburas,
Very sorry for late response.

As I tested, I can reproduce the issue with two of my 4K monitors in case of 2160p60hz.
And I do NOT have the same issue with C2 board.
So I guess this issue is shown only with N2 board and it looks there is no monitor dependency.

If you're available, please try 2160p30hz display manual mode.

Still no update because I was not available to look into this issue because of other issues and features.
Sorry.
I think I can get back to this issue this week.
This problem is considered as high priority issue so I will be back soon.

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Re: HDMI flickering

Unread post by joy » Mon Apr 29, 2019 12:29 pm

robabruton wrote:
Wed Apr 24, 2019 7:48 am
Sorry it has taken me a little while to respond; I'm in the middle of exams at school right now and haven't had much free time. I ordered eMMC memory (running Linux) and out of the box (and after very little testing) I did not have the same flickering issues. I eventually changed my boot settings to what you recommended anyways (2160p30hz, disabled auto detect) and am getting flickering issues again. Not sure what to do. If you need any more info or tests, I'll try to respond back quickly. Thanks for looking into it
bugmenot wrote:
Thu Apr 25, 2019 6:10 pm
I have to confirm this issue.
when using a LG 4k monitor flickering happens (Flickering can be provoked by activity like opening a terminal or moving the mouse).
using different modes (via boot.ini) did not change behavior (using 30Hz might flicker less frequent)
disabling compositor did not change behavior (via Mate Tweak: Windows - Window manager - select: Macro (No compositor))
@robabruton, @bugmenot,
Thanks for sharing your test results.
With 2160p30hz, it looks the issue is also shown, less frequently, but not clearly.

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Re: HDMI flickering

Unread post by Gburas » Mon Apr 29, 2019 2:11 pm

Gburas wrote:on other 4k and 1080p60 screen is still flickering
tv is samsung ue55nu7172u
in a few days i will check with fhd tv screen
As i mentioned I have checked all 2160p modes, on this TV I also have flickering with 1080p60

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Re: HDMI flickering

Unread post by phaseshifter » Mon Apr 29, 2019 4:21 pm

i would try running a 15 volt or higher maybe ...at a supply current of no less than 2 amps.....so far i have noticed that most screen problems are being fixed with higher voltage/current supply's.
why this is i cannot say..i don't have the gear to test myself but i wonder what supply joy is using..???

my 20 cents worth..i don't know if the gpu is demanding heaver than expected lads due to the high processing involved...??.
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Re: HDMI flickering

Unread post by Gburas » Mon Apr 29, 2019 4:30 pm

i have original/official 12v/2a power spplay, bought directly from HK

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Re: HDMI flickering

Unread post by phaseshifter » Mon Apr 29, 2019 4:49 pm

can you obtain a 15 volt 2 amp supply or higher within the voltage range...

it will only draw what current it needs

if you use something like 15 volt 4 amp or 6 amp but do not exceed 20 volts..
Last edited by phaseshifter on Tue Apr 30, 2019 7:32 am, edited 1 time in total.
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Re: HDMI flickering

Unread post by Gburas » Mon Apr 29, 2019 9:12 pm

Can i power board through GPIO pins?

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Re: HDMI flickering

Unread post by tobetter » Tue Apr 30, 2019 1:05 am

Gburas wrote:
Mon Apr 29, 2019 9:12 pm
Can i power board through GPIO pins?
Do you want to supply the power to GPIO pin #2 and #4?
No, many power rail 3.3V, 1.8V and others are from DC input.

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Re: HDMI flickering

Unread post by eval- » Tue Apr 30, 2019 6:58 am

I have exact flickering as in the videos, 4Gb N2 running X11/Mate (no compositing), display is LG 43UD79 (4K).

Only the HK Ubuntu image glitches, not Arch Linux, and not in CoreELEC. (Tho CE won't run at 4k.. and only some 4k demos decode, no 4k movies.. 8 or 10bit, HDR/SDR, x264/hevc, none play... in Ubuntu at least c2play spits up a few frames before the system hangs. Temps look fine, CPU isn't stressed. 1080p plays fine.)

Also, the board does not boot into Petitboot if SPI switch is on... or am I just not getting it displayed @4K? Board came from Pollin.de.

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Re: HDMI flickering

Unread post by phaseshifter » Tue Apr 30, 2019 7:42 am

if your using the spi and petitboot make shure you have an adequate power supply .....12 volt 2 amp is what H-k sell for the N-2...

i use a home brew but i run it at 15 volts..and amps is around 6 amps i guess
you could use an 4 amp supply if you like but don't exceed the voltage of 20 volts..no less than 2 amps

and also if you can see the device it will be generally "nolabel" or sda1 ..mmcblck1. etc,,etc,,.
select the option you want if you have several medias connected then chose what you want to load ...

let it load up there may be no display watch the hdd light`s flashing or the usb lights etc,,etc..and wait about 2 min`s the switch the power to your screen off power of..then power it on again..then you should see your image.etc....or your login..screen..etc..etc

this is the issue i have been having with petitboot..it may be yours too i have to try my other N-2 later see if it is a board issue or what it may be
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Re: HDMI flickering

Unread post by odroid » Tue Apr 30, 2019 8:49 am

This issue seems not to be related to the power supply.
We have to buy some 4K displays to reproduce issue probably.

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Re: HDMI flickering

Unread post by eval- » Wed May 01, 2019 12:15 am

odroid wrote:
Tue Apr 30, 2019 8:49 am
We have to buy some 4K displays to reproduce issue probably.
Why are there no flickering when using Arch Linux for N2 instead of Ubuntu?

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Re: HDMI flickering

Unread post by crashoverride » Wed May 01, 2019 12:48 am

This could possibly be related to this:
viewtopic.php?f=177&p=254311#p254078

If vsync (inside the kernel) is not accurate, then register changes may be happening during the frame display. This is only a theory. Further investigation would be required.

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Re: HDMI flickering

Unread post by eval- » Wed May 01, 2019 5:22 am

crashoverride wrote:
Wed May 01, 2019 12:48 am
This could possibly be related to this:
viewtopic.php?f=177&p=254311#p254078

If vsync (inside the kernel) is not accurate, then register changes may be happening during the frame display. This is only a theory. Further investigation would be required.
Not a bad theory... I have no timing issues under Arch (where I also have no flickering.)

Also, happy (but embarrassed) to announce that all of the issues/crashing I experienced with c2play / CoreELEC for 2160p decode went away once I plugged my HDMI cable into the 60hz jack (my monitor has 4 HDMI in, it seems 2 are only 30Hz.)

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Re: HDMI flickering

Unread post by thatjay » Wed May 01, 2019 8:26 am

I can report that this also happens on the Dell P2715Q 4K monitor. Haven't been able to figure out the cause.

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Re: HDMI flickering

Unread post by wallyz21 » Wed May 01, 2019 5:11 pm

A look at post viewtopic.php?f=177&t=34698 seems to indicate that there are indeed general timing issues with the Ubuntu N2 kernel. Several timing graphs have been provided and all information points in that direction. I have confirmed these timing errors occur on both the desktop and minimal images with the vsync which appears to be the worst affected by these timing issues. A comparison using the same timing test tool shows that the alarm kernel does not exhibit these issues so the hardware is probable not at fault and the power would not then be the issue! By process of elimination the Ubuntu build is the only culprit left!

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Re: HDMI flickering

Unread post by Gburas » Wed May 01, 2019 8:24 pm

today i checked meverics debian image and the flickering is still present (maybe i`m wrong-please correct me- both images shares kernel so my test was pointless?)

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Re: HDMI flickering

Unread post by bugmenot » Thu May 02, 2019 1:24 am

the following fix (or work around) works for me:
1. change governor to performance (see https://wiki.odroid.com/odroid-xu4/appl ... q_govornor)
2. reboot odroid

Note: changing back to "interactive" after boot does not bring back flickering

found this by chance while doing some benchmarks

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Re: HDMI flickering

Unread post by Gburas » Thu May 02, 2019 2:05 pm

bugmenot wrote:the following fix (or work around) works for me:
1. change governor to performance (see https://wiki.odroid.com/odroid-xu4/appl ... q_govornor)
2. reboot odroid

Note: changing back to "interactive" after boot does not bring back flickering

found this by chance while doing some benchmarks
This workaround doesn't work for me, the flickering is still present

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Re: HDMI flickering

Unread post by joy » Fri May 10, 2019 4:28 pm

Hello friends,
As @crashoverride and @wallyz21 mentioned, it looks this issue can be related to vsync timing.

I looked into fb driver to try to adjust vsync waiting timing
and found a point that I can easily test it using dts option pxp_mode in meson_fb driver.

Code: Select all

void osd_wait_vsync_hw(void)
{
	unsigned long timeout;
	if (osd_hw.fb_drvier_probe) {
		vsync_hit = false;

		if (pxp_mode)
			timeout = msecs_to_jiffies(50);
		else
		timeout = msecs_to_jiffies(1000);
		wait_event_interruptible_timeout(
				osd_vsync_wq, vsync_hit, timeout);
	}
}

s64 osd_wait_vsync_event(void)
{
	unsigned long timeout;

	user_vsync_hit = false;

	if (pxp_mode)
		timeout = msecs_to_jiffies(50);
	else
		timeout = msecs_to_jiffies(1000);

	/* waiting for 10ms. */
	wait_event_interruptible_timeout(osd_vsync_wq, user_vsync_hit, timeout);

	return timestamp;
}
https://github.com/hardkernel/linux/blo ... hw.c#L1910
https://github.com/hardkernel/linux/blo ... 2.dts#L369
I've changed to value to pxp_mode=1 and I'm checking the issue using my monitor with 2160p60hz those combination has flickering issue very frequently,
and with this option, the issue is shown less frequently.
Not clearly fixed. :( ....
But, I will keep checking the issue using other monitors and other high resolutions combination.

For test, I attached a dtb file here those parameter is modified. (meson64_odroidn2.dtb.zip)

Code: Select all

	pxp_mode = <1>; /** 0:normal mode 1:pxp mode */
- unzip the attachment
- copy it into boot file system of your card (replace meson64_odroidn2.dtb)

(updated)
I'm using performance governor.

Code: Select all

root@odroid:~# cat /sys/devices/system/cpu/cpufreq/policy0/scaling_governor 
performance
root@odroid:~# cat /sys/devices/system/cpu/cpufreq/policy2/scaling_governor                                               
performance
Attachments
meson64_odroidn2.dtb.zip
(17.66 KiB) Downloaded 14 times

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Re: HDMI flickering

Unread post by Gburas » Fri May 10, 2019 8:27 pm

Unfortunately next week I will be able to try Your fix

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Re: HDMI flickering

Unread post by joy » Mon May 13, 2019 5:45 pm

@Gburas,
Anytime, when you're available. :)

And as I found, you don't need to change your dtb file,
but just add this line your your boot.ini and then reboot your N2.

Code: Select all

fdt set /meson-fb pxp_mode "1"

Code: Select all

# Load kernel, dtb and initrd
fatload mmc ${devno}:1 ${k_addr} Image.gz
fatload mmc ${devno}:1 ${dtb_loadaddr} meson64_odroidn2.dtb
fatload mmc ${devno}:1 ${initrd_loadaddr} uInitrd
fdt addr ${dtb_loadaddr}

### ADD THIS LINE HERE
fdt set /meson-fb pxp_mode "1"

# unzip the kernel
unzip ${k_addr} ${loadaddr}

# boot
booti ${loadaddr} ${initrd_loadaddr} ${dtb_loadaddr}
And can I ask one more thing before the aforementioned try?

I found when I set the default governor as "performance", the flicker issue rarely shows as @bugmenot mentioned.
So before change pxp_mode, could you check it again your default governor is performance?
If not so, please try this set-up.
https://wiki.odroid.com/odroid-xu4/appl ... ufrequtils

Code: Select all

$ sudo systemctl disable ondemand

$ sudo apt-get install cpufrequtils
$ sudo vi /etc/default/cpufrequtils
 
ENABLE="true"
GOVERNOR="performance"

$ sudo service cpufrequtils restart
Thanks!

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Re: HDMI flickering

Unread post by Gburas » Mon May 13, 2019 5:56 pm

Gburas wrote:
Thu May 02, 2019 2:05 pm
bugmenot wrote:the following fix (or work around) works for me:
1. change governor to performance (see https://wiki.odroid.com/odroid-xu4/appl ... q_govornor)
2. reboot odroid

Note: changing back to "interactive" after boot does not bring back flickering

found this by chance while doing some benchmarks
This workaround doesn't work for me, the flickering is still present

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@joy i have already tried this but it didn`t work

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Re: HDMI flickering

Unread post by joy » Tue May 14, 2019 10:57 am

Gburas wrote:
Mon May 13, 2019 5:56 pm
Gburas wrote:
Thu May 02, 2019 2:05 pm
bugmenot wrote:the following fix (or work around) works for me:
1. change governor to performance (see https://wiki.odroid.com/odroid-xu4/appl ... q_govornor)
2. reboot odroid

Note: changing back to "interactive" after boot does not bring back flickering

found this by chance while doing some benchmarks
This workaround doesn't work for me, the flickering is still present

Sent from Moto Z2 Force with Tapatalka
@joy i have already tried this but it didn`t work
@Gburas,
I see.
Thanks for the confirmation.
Once you're available, please check pxp_mode=1 option.

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Re: HDMI flickering

Unread post by Gburas » Mon May 20, 2019 5:10 pm

Hi @joy
i have tried your solution and "probably" flickering appears less often but still remains, I recorded the movie in slow motion with flickering moments around 2:45 and 3:58


also i have upgraded kernel to the latest one before try

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Re: HDMI flickering

Unread post by joy » Tue May 21, 2019 3:52 pm

Gburas wrote:
Mon May 20, 2019 5:10 pm
Hi @joy
i have tried your solution and "probably" flickering appears less often but still remains, I recorded the movie in slow motion with flickering moments around 2:45 and 3:58
Thank you so much for doing the test and sharing detailed result.
Very helpful information even though the approach can't fix it perfectly.

In my case, now I don't see the flickering issue in case of idle display with "performance governor" any more
But it seems high cpu burden affects it.

And can I ask one more?
Please share edid.bin and dmesg log for me here in this thread?
- /media/boot/edid.bin

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Re: HDMI flickering

Unread post by Gburas » Tue May 21, 2019 4:35 pm

here they are:
hdmi-flickering.zip
(587 Bytes) Downloaded 17 times
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Re: HDMI flickering

Unread post by wallyz21 » Thu May 23, 2019 9:13 am

Gburas wrote:
Mon May 20, 2019 5:10 pm
Hi @joy
i have tried your solution and "probably" flickering appears less often but still remains, I recorded the movie in slow motion with flickering moments around 2:45 and 3:58


also i have upgraded kernel to the latest one before try
Have you tried these settings? From this post :

viewtopic.php?f=177&t=34963

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Re: HDMI flickering

Unread post by joy » Thu May 23, 2019 11:33 am

wallyz21 wrote:
Thu May 23, 2019 9:13 am
Have you tried these settings? From this post :

viewtopic.php?f=177&t=34963
Very useful tip.
Gburas wrote:
Tue May 21, 2019 4:35 pm
here they are:
hdmi-flickering.zip
@Gburas,
Thank you for sharing the information.
Display timing looks no specific issue.

I have one that it's worthy to try.

Code: Select all

$ echo 2-5 > /proc/irq/45/smp_affinity_list
irq 45 is assigned to osd-vsync.

If you're available, can you try @wallyz21's approach and mine, too?

I'm still testing this issue
and with lower cpu frequency, the issue is shown more frequently.

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Re: HDMI flickering

Unread post by dbod » Sat Jun 01, 2019 1:12 am

I just tried the
$ sudo systemctl disable ondemand
$ sudo apt-get install cpufrequtils
$ sudo vi /etc/default/cpufrequtils

ENABLE="true"
GOVERNOR="performance"

$ sudo service cpufrequtils restart

method from above, and it worked for me. No more flickering.

I do not yet know what all of this means in terms of power consumption.
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Re: HDMI flickering

Unread post by rhavia » Wed Jun 26, 2019 5:32 pm

Hello,

I had the same issue on my N2 with 4K screen, the last solution solved it, thanks a lot !
Note that the flickering stopped instantly after the service restarted.

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Re: HDMI flickering

Unread post by joy » Mon Jul 01, 2019 8:57 am

So it means default cpu governor have to be "performance" to support 4K without flickering.
I need to check which component (maybe, one of osd block) depends on cpu resource or bandwidth.... just I'm wondering...

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