====== display_tz_enable ======

This function is responsible for effectively setting up the IPU. This is done by configuring the display channel path in <color #088A29>ipu_setup</color> and then enabling the display in <color #088A29>ipu_panel_enable</color>.

  void display_tz_enable(void) {    
    dispDev.type = ipu_display_panel;
    dispDev.width = XGA_FW;
    dispDev.height = XGA_FH;
    
    ipu_setup();
    ipu_panel_enable(dispDev.type);
  }
  
===== ipu_setup =====

This function sets the ipu display channel path, including IDMAC->DMFC->DP->DC->DI->LCD.

The following image available at the official [[http://people.freebsd.org/~gonzo/arm/iMX6-IPU.pdf|IPU doc]], shows the channel path:{{ :ipu-specifics:ipu.png?nolink&700 |}}

In our code, for VGA, only the idmac, dc and di need to be configured:

  void ipu_setup(void) {
    ipu_sw_reset(1000); // reset ipu by SRC(system reset controller)
    
    idmac_config(); // Image DMA Controler
    dc_config();    // Display Controller
    di_config();    // Display Interface
    ipu_enable_display(); // enable both di0 and di1
  }
  
===== ipu_panel_enable =====

This function enables the display panel by resetting it and providing the backlight.

  void ipu_panel_enable(int panel_type_sel) {
    if (dispDev.init_status & (1 << panel_type_sel)) {
        cprintf("the panel has been initialized!!\n");
        return;
    } else {
        dispDev.init_status |= (1 << panel_type_sel);
    }
    
    vga_tve_iomux_config(); // VGA iomux 
    vga_tve_clk_setting();  // VGA clock setting
    vga_tve_config();       // VGA config
  }