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Qt5 / EGL : Wrong frame displayed

Question asked by Pierre-Olivier DI GIUSEPPE on May 14, 2018
Latest reply on May 25, 2018 by Pierre-Olivier DI GIUSEPPE

I'm currently developing a Qt5/EGL app that runs on an iMX6-based board.
I'm using a power-save script to put the display in sleep mode. This script powers off the display and blanks the framebuffer. In case of exit of this mode, the framebuffer is woken up along with the display.


But, sometimes, when we exit the sleep mode, the display turns out to be one frame late.


It seems like Qt5/EGL current drawing frame is actually the same than the one being displayed by HDMI/framebuffer.
Then as long as Qt doesn't write a new frame, we are displaying the old one, so we are one frame late.


Do you guys know where this failed synchronization could come from ?


Thank you, have a nice day