Tearing and drop in FPS after blanking FB

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Tearing and drop in FPS after blanking FB

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mathieuslabbinc
Contributor I

Hi,

I'm having an issue on the i.MX6 duallite platform.

The platform is using a modified version of 3.10.53 BSP with a FB backend.

normally, the main application that runs can get up to around a stable 30fps.

But if the screen is blanked and set back to normal again with:

$ echo 1 > /sys/class/graphics/fb0/blank

$ echo 0 > /sys/class/graphics/fb0/blank

the FPS drops dramatically to around 5 to 10 FPS and tearing is clearly visible.

The only thing I've noticed is this in dmesg:

[  474.915254] mxc_sdc_fb fb.19: MXCFB_WAIT_FOR_VSYNC: timeout 0

The only way to get rid of these issues is restarting the main application, but then again, from the moment you blank the screen, the issues are back.

Any clues/help is much appreciated!

Kr

Mathieu

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mathieuslabbinc
Contributor I

Apparently these exports are related:

export QT_QPA_EGLFS_SWAPINTERVAL=1

export QT_QPA_EGLFS_FORCEVSYNC=1

If I disable those on the 3.10 kernel, it has no effect, tearing still visible.

If I disable them on a 3.14 kernel, the tearing is not immediately reproducible anymore.

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mathieuslabbinc
Contributor I

I've attached some small sample code which on my side also triggers this issue.

Qt 5.5.1 is used to compile it/

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Bio_TICFSL
NXP TechSupport
NXP TechSupport

Hi Mathieu,

Apparently this is a bug present in GPU driver 5.0.11p4 for 3.10.53, I suggest to update to 3.14.28 based BSP in order to upgrade the gpu driver as well. there is no gpu patch for 3.10.53 bsp. Also you can check some suggestions: Bad performance IMX6DL + Wayland + QT + OpenGLES

regards

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mathieuslabbinc
Contributor I

Hi Bio,

I've tried upgrading to 3.14.28 -> same issue.

Also tried upgrading to 3.14.52 -> same issue.

Any further ideas to help resolve this?

Kr

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mathieuslabbinc
Contributor I

Hi,

thanks for pointing this out. Would it be advised to immediately go to 3.14.52 for i.mx6?

Kr

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