feat(lcd): add lcd_pwm_max_limit

huangcm

2025-07-03 571fede27a127398697e783a06a833e37b5b58c3

 longan/kernel/linux-4.9/drivers/video/fbdev/sunxi/disp2/disp/de/disp_lcd.c
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@@ -456,19 +456,27 @@
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 					     2);
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 	}
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+    sprintf(sub_name, "lcd_pwm_max_limit");
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+    ret = disp_sys_script_get_item(primary_key, sub_name, &value, 1);
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+    if (ret == 1) {
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+        lcd_cfg->lcd_pwm_max_limit = value;
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+    } else {
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+        lcd_cfg->lcd_pwm_max_limit = 255;
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+    }
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+
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 /* backlight adjust */
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 	for (i = 0; i < 101; i++) {
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 		sprintf(sub_name, "lcd_bl_%d_percent", i);
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 		lcd_cfg->backlight_curve_adjust[i] = 0;
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 		if (i == 100)
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-			lcd_cfg->backlight_curve_adjust[i] = 255;
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+			lcd_cfg->backlight_curve_adjust[i] = lcd_cfg->lcd_pwm_max_limit;
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 		ret =
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 		    disp_sys_script_get_item(primary_key, sub_name, &value, 1);
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 		if (ret == 1) {
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 			value = (value > 100) ? 100 : value;
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-			value = value * 255 / 100;
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+			value = value * lcd_cfg->lcd_pwm_max_limit / 100;
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 			lcd_cfg->backlight_curve_adjust[i] = value;
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 		}
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 	}
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@@ -476,7 +484,7 @@
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 	sprintf(sub_name, "lcd_backlight");
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 	ret = disp_sys_script_get_item(primary_key, sub_name, &value, 1);
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 	if (ret == 1) {
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-		value = (value > 256) ? 256 : value;
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+		value = (value > lcd_cfg->lcd_pwm_max_limit) ? lcd_cfg->lcd_pwm_max_limit : value;
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 		lcd_cfg->backlight_bright = value;
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 	} else {
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 		lcd_cfg->backlight_bright = 197;