The time taken from POR to when the display comes up is noted to be approximately 680ms. The General Purpose Input-Output (GPIO) pin settings, by default, are in Off state. The direction and value of this GPIO pin is set to high, just after the video_bmp_display() function, which displays a .bmp file onto the panel. OSPI NOR is used as boot-media for testing purposes.

• GPIO0_39 on the user expansion connector-pin 18, is used for time measurements. To set the direction of this pin to output, and the state of this pin to high, use the following code:

  — a/common/bmp.c
  +++ b/common/bmp.c
  @@ -19,6 +19,7 @@
  #include <splash.h>
  #include <video.h>
  #include <asm/byteorder.h>
  +#include <asm/io.h>
  
  /*
  
  Allocate and decompress a BMP image using gunzip().
  @@ -142,6 +143,11 @@ int bmp_display(ulong addr, int x, int y)
  ret = video_bmp_display(dev, addr, x, y, align);
  }
  
  + writel(0x00050007, 0x000F40A0);
  + writel(0xFFFFFF7F, 0x00600038);
  + writel(0x80, 0x00600040);
  +
  if (bmp_alloc_addr)
  free(bmp_alloc_addr);

• To enable the GPIO driver, if not done already, use the following config options in the am62px_evm_r5_defconfig file:

  +CONFIG_SPL_GPIO=y
  +CONFIG_GPIO=y
  +CONFIG_DM_GPIO=y
  +CONFIG_DA8XX_GPIO=y
  +CONFIG_CMD_GPIO=y

• To set the pin multiplexer (pinmux) of the GPIO pin number GPIO0_39, use the device tree pinmux settings as mentioned in the following code:

  diff --git a/arch/arm64/boot/dts/ti/k3-am62p5-sk.dts b/arch/arm64/boot/dts/ti/k3-am62p5-sk.dts
  index 4b8e7964ca4d..7dbf5e9b9c2b 100644
  --- a/arch/arm64/boot/dts/ti/k3-am62p5-sk.dts
  +++ b/arch/arm64/boot/dts/ti/k3-am62p5-sk.dts
  @@ -232,6 +232,10 @@ hdmi_connector_in: endpoint {
   
   &main_gpio0 {
   	bootph-all;
  +
  +	status = "okay";
  +	pinctrl-names = "default";
  +	pinctrl-0 = <&test_gpio_default>;
   };
   
   &main_gpio1 {
  @@ -446,6 +450,12 @@ AM62PX_IOPAD(0x0078, PIN_OUTPUT, 1) /* (AC24) GPMC0_AD15.VOUT0_DATA23 */
   			AM62PX_IOPAD(0x009c, PIN_OUTPUT, 1) /* (AD24) GPMC0_WAIT1.VOUT0_EXTPCLKIN */
   		>;
   	};
  +
  +	test_gpio_default: test-gpio {
  +        pinctrl-single,pins = <
  +			AM62PX_IOPAD(0x00a0, PIN_INPUT, 7) /* (P24) GPMC0_WPn.GPIO0_39 */
  +		>;
  +	};
   };
   
   &main_i2c0 {
  @@ -789,6 +799,7 @@ &mcu_r5fss0_core0 {
   &main_uart0 {
   	pinctrl-names = "default";
   	pinctrl-0 = <&main_uart0_pins_default>;
  +	test-gpios = <&main_gpio0 39 GPIO_ACTIVE_HIGH>;
   	interrupts-extended = <&gic500 GIC_SPI 178 IRQ_TYPE_LEVEL_HIGH>,
   			<&main_pmx0 0x1c8>; /* (D14) UART0_RXD PADCONFIG114 */
   	interrupt-names = "irq", "wakeup";

• Next, connect the GPIO pin and MCU_PORz to the logic analyzer and measure the time difference between the two to get the accurate timestamp.