EGLFS frame jitter issue in panel with unusual aspect ratio.

reliq-bot

Hi there,

Last couple of weeks I am trying to debug a rendering issue between eglfs and an unusual aspect ratio. I have a 1920x515@59.6Hz panel. My linux image has Qt5, EGLFS and EGL support. Trying with a 2d painter example I get the following result (video): To my understanding it looks like frame jitter/scrumbling.
All QtQuick examples have the same behaviour but openGL examples (like the hellogl2) will work with no issues.

I attempted to debug the issue in the following ways:

For start I tried the same linux image with a different display (480x800@60Hz) and no issues there
Then I tried the same panel into a linux image with weston-wayland support and again all good.
I tried to set all related environment variable with no success: QT_QPA_FORCEVSYNC, QT_QPA_FORCE888, QT_QPA_ALWAYS_SET_MODE, custom KMS configs etc.
I also attempted to change the panel timings to a second available mode (48.08Hz) this made the issue less visible but still quite apparent.
Observing the eglfs debug log I could not see any issues (log below)

QML debugging is enabled. Only use this in a safe environment.
Failed to move cursor on screen DSI1: -14
Failed to move cursor on screen DSI1: -14
Shmem has been moved to thread
shmemThread has started
Created context for format QSurfaceFormat(version 2.0, options QFlags<QSurfaceFormat::FormatOption>(), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize -1, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 1, colorSpace QSurfaceFormat::DefaultColorSpace, profile  QSurfaceFormat::NoProfile) with config:
	EGL_BUFFER_SIZE: 24
	EGL_ALPHA_SIZE: 0
	EGL_BLUE_SIZE: 8
	EGL_GREEN_SIZE: 8
	EGL_RED_SIZE: 8
	EGL_DEPTH_SIZE: 24
	EGL_STENCIL_SIZE: 8
	EGL_CONFIG_CAVEAT: 12344
	EGL_CONFIG_ID: 15
	EGL_LEVEL: 0
	EGL_MAX_PBUFFER_HEIGHT: 8064
	EGL_MAX_PBUFFER_PIXELS: 65028096
	EGL_MAX_PBUFFER_WIDTH: 8064
	EGL_NATIVE_RENDERABLE: 1
	EGL_NATIVE_VISUAL_ID: 875713112
	EGL_NATIVE_VISUAL_TYPE: 32
	EGL_SAMPLES: 0
	EGL_SAMPLE_BUFFERS: 0
	EGL_SURFACE_TYPE: 1287
	EGL_TRANSPARENT_TYPE: 12344
	EGL_TRANSPARENT_BLUE_VALUE: -1
	EGL_TRANSPARENT_GREEN_VALUE: -1
	EGL_TRANSPARENT_RED_VALUE: -1
	EGL_BIND_TO_TEXTURE_RGB: 1
	EGL_BIND_TO_TEXTURE_RGBA: 1
	EGL_MIN_SWAP_INTERVAL: 1
	EGL_MAX_SWAP_INTERVAL: 60

Double checking the panel mode I could also see no obvious issues besides the unusual aspect ratio and framerate

4      33      connected       DSI-1           309x83          1       33
  modes:
        index name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot
  #0 1920x515 48.08 1920 1980 2000 2080 515 525 560 565 56500 flags: nhsync, nvsync; type: preferred, driver
  props:
        1 EDID:
                flags: immutable blob
                blobs:

                value:
        2 DPMS:
                flags: enum
                enums: On=0 Standby=1 Suspend=2 Off=3
                value: 0
        5 link-status:
                flags: enum
                enums: Good=0 Bad=1
                value: 0
        6 non-desktop:
                flags: immutable range
                values: 0 1
                value: 0
        4 TILE:
                flags: immutable blob
                blobs:

At this point I could not find any other pointers to investigate the issue.

Any ideas will be highly appreciated!

All the best,
Kyr.