LVGL flush callback with DMA2D

The code

Embedded C for Cortex-M. It compiles. There are 3 real bugs in it: the kind that pass a bench test and fail in the field.

void my_flush_cb(lv_display_t *disp, const lv_area_t *area,
                 uint8_t *px)
{
    int32_t w = area->x2 - area->x1;
    int32_t h = area->y2 - area->y1;
    dma2d_copy(px, fb, area->x1, area->y1, w, h);
}

What an interviewer expects

• Point to each line you'd stop in a code review.
• Say what actually breaks: the failure mode, not just the rule it violates.
• Fix it, then defend the fix when asked the follow-up.

The bugs, reference fixes and the follow-up question are in the practice app, after you've tried it.

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