FrameBuffer scale issue on linux target



  • Hi,
    We are running embedded QT on ZynqMP platform.
    For Display we are using Display Port controller.
    Display Port is configured to enable two layers i.e one is graphics layer (for custom application) and other is video layer(for GUI).

    Requirement is to run QT resolution in multiple resolution.
    To change the resolution we use drmModeSetCrtc API and we could able the see the resolution change on display.
    But when we read the frame buffer resolution using ioctl call FBIOGET_VSCREENINFO, we find the resolution of frame buffer is not updating.

    Can someone give me a hint regarding this issue.

    Thanks
    Tirupathi



  • @Tirupathi-Korla Hey! Have you solved you problem? I met the similar problem. Qt app works fine when using 1280x720. But when change to 1920x1080, the app doesn't show up without any error.

    I change screen resolution in this way:

    1. Call target api to change resolution in HDMI conf. And I find that /proc/umap/hdmi0 has set "Current Format" to "1080P_60 16:9(VIC=16)".
    2. Call "ioctl" to change resolution in fb conf. And in /proc/umap/hifb0 "xres" and "yres" has been changed too.

    Everything seems OK, but nothing show up. Do you have any idea?



  • No.
    Are you using ZynqMP platform? Try changing resolution using set mode API in drm library.


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