RK3588S Andriod12调试OLED屏幕背光

OLED屏幕不同于普通LED屏幕，不需要单独的背光模块。其背光亮度调节是通过MIPI发送命令调整的，一般调节OLED亮度的命令都是0x51，亮度值范围为0-0xff（即0-255）。

实现OLED背光亮度可调节，需要做如下修改：

1，dts中屏蔽背光相关节点，如下：

        backlight: backlight { -               status = "okay"; +               status = "disabled";                 compatible = "pwm-backlight";                 pwms = ;                 brightness-levels =        0,1,2,3,4,5,6,7,8,9,10,        11,12,13,14,15,16,17,18,19,20,        21,22,23,24,25,26,27,28,29,30,        31,32,33,34,35,36,37,38,39,40,        41,42,43,44,45,46,47,48,49,50,        51,52,53,54,55,56,57,58,59,60,        61,62,63,64,65,66,67,68,69,70,        71,72,73,74,75,76,77,78,79,80,        81,82,83,84,85,86,87,88,89,90,        91,92,93,94,95,96,97,98,99,100,        101,102,103,104,105,106,107,108,109,110,        111,112,113,114,115,116,117,118,119,120,        121,122,123,124,125,126,127,128,129,130,        131,132,133,134,135,136,137,138,139,140,        141,142,143,144,145,146,147,148,149,150,        151,152,153,154,155,156,157,158,159,160,        161,162,163,164,165,166,167,168,169,170,        171,172,173,174,175,176,177,178,179,180,        181,182,183,184,185,186,187,188,189,190,        191,192,193,194,195,196,197,198,199,200,        201,202,203,204,205,206,207,208,209,210,        211,212,213,214,215,216,217,218,219,220,        221,222,223,224,225,226,227,228,229,230,        231,232,233,234,235,236,237,238,239,240,        241,242,243,244,245,246,247,248,249,250,        251,252,253,254,255 };

之后在dcs_bl_update_status函数中做个映射，通过调整brightness_table中的值就可以对背光亮度的调节曲线作出调整。如下：

static int dcs_bl_update_status(struct backlight_device *bl) {     struct panel_simple *p = bl_get_data(bl);     struct mipi_dsi_device *dsi = p->dsi;     int ret;     u16 brightness;

    if (!p->prepared)         return 0;

    dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;     brightness = brightness_table[bl->props.brightness];//映射     ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness/*bl->props.brightness*/);     if (ret < 0)         return ret;

    dsi->mode_flags |= MIPI_DSI_MODE_LPM;

    return 0; }