[Beijing Xunwei] i.MX6ULL Terminator Linux LCD driver experimental operation test

1 Basic test of LCD screen

1. Compile the device tree file
Configure the device tree file according to the previous configuration. After recompiling the device tree file, start the development board with the new device tree file.

2. Enable the Linux kernel logo display.
When the Linux kernel is started, you can choose to display the little penguin logo icon. As long as the kernel logo icon is displayed normally, the LCD driver is basically working normally. Let's configure the kernel and select the kernel to display the logo when it starts.
First use the "make ARCH=arm menuconfig" command to open the Linux kernel graphical configuration interface, and follow the path below to find the logo configuration options:

Device Drivers  --->
Graphics support  --->
[*] Bootup logo  --->
[*]   Standard black and white Linux logo
[*]   Standard 16-color Linux logo
[*]   Standard 224-color Linux logo

As shown in Figure 1.1:

Figure 1.1

The three options in the picture correspond to the logos in black and white, 16-bit, and 24-bit color formats. We select all three and compile them into the Linux kernel. After setting, save and exit, recompile the Linux kernel, use the newly compiled topeet_emmc_4_3.dtb and zImage mirroring to start the system after the compilation is complete, if the LCD driver works normally, a colorful little penguin logo will appear in the upper left corner of the LCD screen. The background color is black, as shown in Figure 1.2:

Figure 1.2

2 LCD backlight adjustment

There are 8 backlight adjustment levels set under the backlight node in the device tree, which can be set from 0 to 7. The brightness of the LCD backlight can be adjusted by setting the backlight level. After the development board is started, enter the following directory:
cd /sys/devices/platform/backlight/backlight/backlight/
There are the following files in this directory:

Figure 2.1

Among them, brightness represents the current brightness level, and max_bgigntness represents the maximum brightness level. As shown in Figure 2.2:

Figure 2.2

It can be seen that the maximum backlight level is 7, and the current backlight level is 6. If we want to modify the screen brightness, we only need to write the screen brightness level that needs to be set to brightness. For example, set the screen brightness level to 7, then you can use the following command: After
echo 7 > brightness
entering the above command, you will find that the screen brightness increases. If you set the brightness to 0, the LCD backlight will be turned off and the screen will go out.