MTK lcd背光控制软件设计.doc

MTK 配置lcd背光 1 配置lcm背光的控制脚 2 配置uboot 2.1 mediatek/custom/bbk75_ics/uboot/cust_leds.c 2.2 mediatek/platform/mt6575/uboot/mt65xx_leds.c 3 配置kernel 3.1 mediatek/custom/bbk75_ics/kernel/leds/mt65xx/cust_leds.c 3.2 mediatek/source/kernel/drivers/leds/leds.c 4 注意事项 配置lcm背光的控制脚lcm背光控制主要有两个引脚：使能脚EN和亮度控制引脚VFB。使能脚用来控制背光的使能与否，比如这里是1为enable，0为disable；亮度控制引脚则是用来接PWM输出，通过PWM的占空比来控制背光亮度，这里是低为亮，高为灭。所以在这两个引脚的连接和配置上要保证EN连接至gpio上，而VFB则连接至BB的PWM输出口，然后通过dct工具将上述引脚配置成对应的mode。配置ubootmediatek/custom/bbk75_ics/uboot/cust_leds.c在 cust_led_list数组中更改 lcd-backlight的配置为pwm：static struct cust_mt65xx_led cust_led_listMT65XX_LED_TYPE_TOTAL = ./lcd-backlight, MT65XX_LED_MODE_CUST, (int)DISP_SetBacklight,0,lcd-backlight, MT65XX_LED_MODE_PWM, PWM1,0,;mediatek/platform/mt6575/uboot/mt65xx_leds.c在 mt65xx_led_set_cust中添加对lcm使能脚的控制，以更好地对屏幕的亮灭进行控制：.case MT65XX_LED_MODE_PWM:if(strcmp(cust-name,lcd-backlight) = 0)if(level = 0)mt_set_gpio_out(BACKLIGHT_EN_PIN,GPIO_OUT_ZERO);elseif (level data, level,&(cust-config_data);udelay(10000);mt_set_gpio_out(BACKLIGHT_EN_PIN,GPIO_OUT_ONE); /return brightness_set_pwm(cust-data, level,&cust-config_data);elsereturn led_set_pwm(cust-data, level);return 1;case MT65XX_LED_MODE_GPIO:.以下两个函数同步更改：void mt65xx_backlight_on(void)printf(LEDSuboot: mt65xx_backlight_on nr);mt_set_gpio_mode(BACKLIGHT_EN_PIN, GPIO_MODE_00);/ GPIO MODEmt_set_gpio_dir(BACKLIGHT_EN_PIN, GPIO_DIR_OUT);mt_set_gpio_out(BACKLIGHT_EN_PIN, GPIO_OUT_ONE); mt65xx_leds_brightness_set(MT65XX_LED_TYPE_LCD, LED_FULL);void mt65xx_backlight_off(void)printf(LEDSuboot: mt65xx_backlight_off nr);mt_set_gpio_mode(BACKLIGHT_EN_PIN, GPIO_MODE_00);/ GPIO MODEmt_set_gpio_dir(BACKLIGHT_EN_PIN, GPIO_DIR_OUT);mt_set_gpio_out(BACKLIGHT_EN_PIN, GPIO_OUT_ZERO); mt65xx_leds_brightness_set(MT65XX_LED_TYPE_LCD, LED_OFF);配置kernelmediatek/custom/bbk75_ics/kernel/leds/mt65xx/cust_leds.c将背光led的控制方式更改为pwm：static struct cust_mt65xx_led cust_led_listMT65XX_LED_TYPE_TOTAL = ./lcd-backlight, MT65XX_LED_MODE_CUST, (int)Cust_SetBacklight,0,lcd-backlight, MT65XX_LED_MODE_PWM, PWM1,0, ;mediatek/source/kernel/drivers/leds/leds.c和uboot一样，在 mt65xx_led_set_cust中添加对lcm使能脚的控制，以更好地对屏幕的亮灭进行控制：if (level LED_FULL)level = LED_FULL;else if (level name, cust-mode, level);switch (cust-mode) case MT65XX_LED_MODE_PWM:if(strcmp(cust-name,lcd-backlight) = 0)bl_brightness = level;if(level = 0)mt_set_gpio_out(BACKLIGHT_EN_PIN,GPIO_OUT_ZERO);mt_set_pwm_disable(cust-data);mt_power_off (cust-data);elselevel = brightness_mapping(tmp_level);if(level 0 & level 20 ) level = 20;/45if ( level 244 & level 54) level = 54;backlight_set_pwm(cust-data, level, bl_div,&(cust-config_data);mt_set_gpio_out(BACKLIGHT_EN_PIN,GPIO_OUT_ONE); bl_duty = level;elseif(level = 0)led_tmp_setting.nled_mode = NLED_OFF;elseled_tmp_setting.nled_mode = NLED_ON;led_set_pwm(cust-data,&led_tmp_setting);return 1; case MT65XX_LED_MODE_GPIO:注意事项如果uboot中将VFB配置成了gpio并且输出低使背光一直保持全亮，在进入kernel后通过代码再将其设置为pwm模式，这理应是ok的；但现实就是不行，这样会导致背光不能调节（不过由于没有量波形，故不知是有波形输出还是仍一直输出低电平），就在这里耗时较长，所以关注一下这点。附修改记录：Modified : /trunk/ALPS.ICS.MP.V1_T_20120405/mediatek/custom/bbk15_td_ics/kernel/leds/mt65xx/cust_leds.cModified : /trunk/ALPS.ICS.MP.V1_T_20120405/mediatek/custom/bbk15_td_ics/uboot/cust_leds.cModifi