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backlight or framebuffer problem?

Kevin Chow
Expert 1625 points
Other Parts Discussed in Thread: AM3517

Hi,

My Test Environment:

Processor: AM3517
TI Android DevKit: TI Android GingerBread 2.3 DevKit 1.0
Platform:  Custom board with 7" LCD (800*480)
Kernel: 2.6.32 

My problem:

The display during  booting is varying:

during x-loader boot: black
during u-boot boot: black
during kernel  boot: black, then random display or last shutdown screen
during system boot: android robot, animation, then system ui.

I want to clear the random display during kernel booting, I think maybe back-light is enabled earlier than clearing video buffer, can we first clear video buffer, and then enable back-light?

In arch/arm/mach-omap2/board-am3517evm.c, the function am3517_evm_display_init() can enable the back-light,

Where can I clear video buffer during the initiation, and how to arrange the sequence of the back-light and display?

Any other solution to this problem?

 

Thanks,

Kevin

 

 

  • 0
    TI__Expert 5400 points

    Hi Kevin,

    Will you please post this query to http://e2e.ti.com > Embedded Software > Linux forum.

    One of our expert from this forum may be able to help you out.

     

    Regards,

    Pankaj Bharadiya

  • 0 in reply to Pankaj Bharadiya
    Expert 1625 points

    Hi Pankaj Bharadiya,

    I will post such query in that forum next time, and this time I have not found way to do it, it seems I don't have the ability to move query, will you help me do this, or let somebody help do it?

     

    Thanks,

    Kevin

  • 0
    Expert 1625 points

    I copied the function am3517_evm_display_init from kernel/arch/arm/mach-omap2/board-am3517evm.c to kernel/driver/video/omap2/dss/dpi.c,   and made some changes.

    @kernel/driver/video/omap2/dss/dpi.c
    @line 264
    dpi_display_enable
    -----------------from-----------------
    dssdev->state = OMAP_DSS_DISPLAY_ACTIVE;
    return 0;

    -------------------to-------------------
    dssdev->state = OMAP_DSS_DISPLAY_ACTIVE;
    am3517_evm_display_init();
    return 0;

    and comment off
    // omap_mux_init_gpio(LCD_PANEL_PWR, OMAP_PIN_INPUT_PULLUP);
    // omap_mux_init_gpio(LCD_PANEL_BKLIGHT_PWR, OMAP_PIN_INPUT_PULLDOWN);
    // omap_mux_init_gpio(LCD_PANEL_PWM, OMAP_PIN_INPUT_PULLDOWN);

    other MACRO should also be copied .

    Maybe this is not a good way, but it works.

    Thanks,

    Kevin