MTK6515 配置lcd背光
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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uboot
mediatek/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_list[MT65XX_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); }else { if (level < 80) level =80; level = level/4; brightness_set_pwm(cust->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); } else { return 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("[LEDS]uboot: mt65xx_backlight_on \n\r"); mt_set_gpio_mode(BACKLIGHT_EN_PIN, GPIO_MODE_00);// GPIO MODE mt_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("[LEDS]uboot: mt65xx_backlight_off \n\r"); mt_set_gpio_mode(BACKLIGHT_EN_PIN, GPIO_MODE_00);// GPIO MODE mt_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kernel
mediatek/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_list[MT65XX_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 < 0) level = 0; mt_set_gpio_mode(BACKLIGHT_EN_PIN, GPIO_MODE_GPIO); mt_set_gpio_dir(BACKLIGHT_EN_PIN, GPIO_DIR_OUT); mt_set_gpio_mode(BACKLIGHT_VFB_PIN, GPIO_MODE_01); mt_set_gpio_dir(BACKLIGHT_VFB_PIN, GPIO_DIR_OUT); //GPIO_PWM_1_PIN_M_PWM printk("mt65xx_leds_set_cust: set brightness, name:%s, mode:%d, level:%d\n", cust->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); }else { level = brightness_mapping(tmp_level); if(level > 0 && level < 20 ) level = 20;//45 if ( level < 195 ) { level=(level-20)/7; } else { level=level - 20 ; level=(level-175)/4; level=level+25; } if (level > 244 && level < 255) level =244; //level 37 //if (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; }else { if(level == 0) { led_tmp_setting.nled_mode = NLED_OFF; }else { led_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.c Modified : /trunk/ALPS.ICS.MP.V1_T_20120405/mediatek/custom/bbk15_td_ics/uboot/cust_leds.c Modified : /trunk/ALPS.ICS.MP.V1_T_20120405/mediatek/platform/mt6575/uboot/mt65xx_leds.c Modified : /trunk/ALPS.ICS.MP.V1_T_20120405/mediatek/source/kernel/drivers/leds/leds.c