i.MX8 EVK, Flicker on Dual Display

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i.MX8 EVK, Flicker on Dual Display

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Contributor III

Hi,

We are seeing a window flickering issue while using the Dual display setup in the i.MX8 EVK. This issue is visible if we driving the LCDIF at resolution of 1080p. In EVK Test setup we have two LCDs connected to the EVK both having resolution of 1080p. In EVK Dual Display configuration is as follows.

DCSS -> HDMI -> HDMI Display
LCDIF -> MIPI DSI -> MIPI DSI to HDMI bridge -> HDMI Display

If we are using 720p resolution for LCDIF not seeing this issue (by default this is the resolution of LCDIF in EVK).  Sometime flickering area becomes more.

Questions:

1. Any one tested 1080p Dual Display playback in i.MX8 EVK /experienced same issue?

2. We could see a post of similar issue in following link. But we could not apply these patches because our kernel version is 4.5.91. As per the link the patches are to be applied in 4.14.98, but when we downloaded this version we could not find the files as said in patch (e.g. file drivers/gpu/drm/bridge/nwl-dsi.c is not present in this path)


   https://community.nxp.com/thread/510810

   LVDS panel flicker issues on imx8mq   

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3 Replies

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NXP TechSupport
NXP TechSupport

what dtb do you use? fsl-imx8mq-evk-dual-display.dtb? when the board boot up, you can find flicker on the hdmi display? because I tested dual display(4k+1080) successfully, do you have find this issue on boot up or playback video?

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Contributor III

Yes we used "fsl-imx8mq-evk-dual-display.dtb" with minor change for setting the resolution of LCDIF to 1080p. 

In EVK based test setup, one HDMI display is connected to HDMI port of EVK.

Second HDMI display is connected to the MIPI DSI HDMI bridge. We need to drive this second display in 1080p resolution.

Default resolution of the LCDIF is given as 720p in file "fsl-imx8mq-evk-dual-display.dts"

This was changed to 1080p. For the HDMI out of i.MX8. Change is only in following line.

&lcdif {
max-res = <1920>, <1080>; /*To test flickering issue */

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NXP TechSupport
NXP TechSupport

now did you use 4.14.98? why don't you find nwl-dsi.c? did you try the patch?

nwl-dsi.c\bridge\drm\gpu\drivers - linux-imx - i.MX Linux kernel 

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