LCD interface flicker when HDMI/DVI enabled

[danielleloader]

Hi,

We noticed that when we try to enable the HDMI/DVI output in the kernel and the device tree, sometimes the LCD (RGB parallel) screen output is flickering. I've not been able to test it on many devices but it's 100% percent reproducible on those I've tested with this particular method:

We are using 1280x800 displays in the product so we configure these screens for this.

IPU1 DISP0 "sin1" mode for single LVDS display.

IPU0 DISP0 for the LCD.

IPU0 DISP1 for the DVI.

Then we've forced the DVI resolution to 1280x800 as it not in the "modes" list in sysfs by default with the following fbset command:

fbset -fb /dev/fb3 -g 1280 800 1280 800 16 -t 14063 40 40 10 3 80 10

Everything is working fine so far.

But when we try to set the resolution to 1280x720 on the DVI, we get a flickering screen on the LCD interface:

echo U:1280x720p-60 >/sys/class/graphics/fb3/mode

Then everything works well again if we set back to 1280x800:

echo U:1280x800p-60 >/sys/class/graphics/fb3/mode

More interestingly there is no flickering and everything works well when we set the resolution to 1080p first, then 720p:

echo U:1920x1080p-60 >/sys/class/graphics/fb3/mode

No flickering.

echo U:1280x720p-60 >/sys/class/graphics/fb3/mode

No flickering.

echo U:1280x800p-60 >/sys/class/graphics/fb3/mode

No flickering.

echo U:1280x720p-60 >/sys/class/graphics/fb3/mode

The LCD flickers again.

Have you ever met this problem? Is there a solution or workaround for this?

Is there a way to somehow routing the data provided by IDMAC (Image DMA Controller) for both DI (Display Interface) on same IPU? If yes, can you explain how?

Thank you

[pinglisui]

Hi, Danielle Loader,

     I had read your topic Direct MAC-MAC connection to Ethernet switch without a PHY .

     Now, I use the same scheme as yours. And now I met the same problem as yours. I am sure that my  ENET_REF_CLK pin has no problem. But I am not very  familiar with 88E6350R. Can you tell me the way you did in your u-boot and your Linux kernel? I wish you could give me some advices and share me your source code about this module in your u-boot and your linux kernel. My E-mail: suipingli@chinaxidian.com

     Thank you!

[Yuri]

Hello,

  You may try gstreamer pipeline of section 7.3.1.6.2 (Routing the same video to different displays)

in "i.MX_Linux_User's_Guide.pdf".

http://www.nxp.com/webapp/Download?colCode=L3.14.52_1.1.0_LINUX_DOCS&Parent_nodeId=13376994810717061...

Have a great day,
Yuri

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