V8 display driver (double buffer) low FPS & high CPU

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42

Hi @pete-pjb @kisvegabor, this is my test:

Target:

  • disp: 800X480
  • ram: <120K
  • psram: 8M

lvgl version:
8.3.3

image
image1268×438 28.6 KB

Question:
In demo 1, may be the implementation B is the best, but in demo 2, it’s the worst. so I need know which implementation is best on my device?

note:
Implementation B: It is implemented according to @pete-pjb code
Implementation C: in flush_cb, copy data to 800X480X2 psram.

43

I suggest “C”. It uses the least RAM and results in the best performance in demo 1 and almost as good as the best in demo 2.

1 Like
44

Hi @kisvegabor
I’m facing same issue that LVGL fps is too low in my device.
I have tried separating the draw buffer into 1/8 of the displaybuffer.
My panel’s resolution is 1280*720, and I only have a 256K ram can be used. So I set the draw buffer to 1/8 as 38400.
But in the draw_bg() in lv_draw_sw_rect.c
the function continued to draw the buffer over the draw buffer size so it will cause memory overwrite.

image
image1920×756 185 KB

As you can see in the Image, the function draw the buffer over 720/8=90 in vertical.
I wonder how to resolve it? Below is the related code
Thanks for your help.


AT_NONCACHEABLE_SECTION_ALIGN(uint8_t s_displayFrameBuffer[1][APP_PANEL_HEIGHT * APP_PANEL_WIDTH * APP_BPP ],
                              APP_PANEL_FB_ADDR_ALIGN_BYTE);

AT_NONCACHEABLE_SECTION_ALIGN(uint8_t draw_buf[APP_PANEL_HEIGHT * APP_PANEL_WIDTH * 2 / 8],
                              APP_PANEL_FB_ADDR_ALIGN_BYTE);


static void littlevgl_flush_callback(lv_disp_drv_t *disp_drv, const lv_area_t *area, lv_color_t *color_p)
{
  
#if 1
    uint32_t bufferAddr = 0;

    uint32_t w = lv_area_get_width(area);
    uint32_t y;
          while (APP_IsContentStreamShadowPending())
        {
        }
        copy_area(area, color_p, (uint8_t*)s_displayFrameBuffer, APP_PANEL_WIDTH * 2);
        APP_TriggerContentStreamShadowLoad();
        lv_disp_flush_ready(disp_drv);
        
#else
        xSemaphoreGive(lvglSemaphore);
        while (APP_IsContentStreamShadowPending())
        {
        }
        lv_disp_flush_ready(disp_drv);
#endif


}

void lv_port_disp_init(void)
{
    static lv_disp_draw_buf_t disp_buf;

    memset(s_displayFrameBuffer, 0, ARRAY_SIZE(s_displayFrameBuffer));
    lv_disp_draw_buf_init(&disp_buf, draw_buf, NULL , APP_PANEL_FB_STRIDE_PIXEL * APP_FB_HEIGHT* APP_BPP/8);

    /*-----------------------------------
     * Register the display in LittlevGL
     *----------------------------------*/
    static lv_disp_drv_t disp_drv;
          /*Descriptor of a display driver*/
    lv_disp_drv_init(&disp_drv); /*Basic initialization*/

    /*Set up the functions to access to your display*/

    /*Set the resolution of the display*/
    disp_drv.hor_res = APP_FB_WIDTH;
    disp_drv.ver_res = APP_FB_HEIGHT;

    /*Used to copy the buffer's content to the display*/
    disp_drv.flush_cb = littlevgl_flush_callback;

    /*Set a display buffer*/
    disp_drv.draw_buf = &disp_buf;
    /*Finally register the driver*/
    lv_disp_drv_register(&disp_drv);
}

Regards,
Joseph