内核启动后，lcd显示logo失败

针对-s5pv210，但对其他平台也使用

lcd显示logo失败，若显示成功默认的logo是一只企鹅，但是串口打印“Start display and show logo”，但是LCD屏没有显示

[    0.833071] s3cfb s3cfb: [fb2] dma: 0x465ab000, cpu: 0xe1000000, size: 0x005dc000
[    0.845112] FIMD src sclk = 166750000
[    0.965701] s3cfb s3cfb: registered successfully
[    0.965744] Start display and show logo

原因：LCD驱动有问题。

第一步：在arch/arm/mach-s5pv210/mach-smdkc110.c当中，约712行，将之前的LCD初始化删掉，并修改如下:

#ifdef CONFIG_FB_S3C_LTE480WV
static struct s3cfb_lcd wvga_s70 = {

        .width = 800,
        .height = 480,
        .p_width = 154,
        .p_height = 96,
        .bpp = 32,
        .freq = 65,

        .timing = {
                .h_fp = 80,
                .h_bp = 36,
                .h_sw = 10,
                .v_fp = 22,
                .v_fpe = 1,
                .v_bp = 15,
                .v_bpe = 1,
                .v_sw = 8,
        },
        .polarity = {
                .rise_vclk = 0,
                .inv_hsync = 1,
                .inv_vsync = 1,
                .inv_vden = 0,
        },
};

static void lcd_cfg_gpio(struct platform_device *pdev)
{
    int i;

    for (i = 0; i < 8; i++) {
        s3c_gpio_cfgpin(S5PV210_GPF0(i), S3C_GPIO_SFN(2));
        s3c_gpio_setpull(S5PV210_GPF0(i), S3C_GPIO_PULL_NONE);
    }

    for (i = 0; i < 8; i++) {
        s3c_gpio_cfgpin(S5PV210_GPF1(i), S3C_GPIO_SFN(2));
        s3c_gpio_setpull(S5PV210_GPF1(i), S3C_GPIO_PULL_NONE);
    }

    for (i = 0; i < 8; i++) {
        s3c_gpio_cfgpin(S5PV210_GPF2(i), S3C_GPIO_SFN(2));
        s3c_gpio_setpull(S5PV210_GPF2(i), S3C_GPIO_PULL_NONE);
    }

    for (i = 0; i < 4; i++) {
        s3c_gpio_cfgpin(S5PV210_GPF3(i), S3C_GPIO_SFN(2));
        s3c_gpio_setpull(S5PV210_GPF3(i), S3C_GPIO_PULL_NONE);
    }

    /* mDNIe SEL: why we shall write 0x2 ? */
    writel(0x2, S5P_MDNIE_SEL);

    /* drive strength to max */
    writel(0xaaaaaaaa, S5PV210_GPF0_BASE + 0xc);
    writel(0xaaaaaaaa, S5PV210_GPF1_BASE + 0xc);
    writel(0xaaaaaaaa, S5PV210_GPF2_BASE + 0xc);
    writel(0x000000aa, S5PV210_GPF3_BASE + 0xc);
}

#define S5PV210_GPD_0_0_TOUT_0  (0x2)
#define S5PV210_GPD_0_1_TOUT_1  (0x2 << 4)
#define S5PV210_GPD_0_2_TOUT_2  (0x2 << 8)
#define S5PV210_GPD_0_3_TOUT_3  (0x2 << 12)
static int lcd_backlight_on(struct platform_device *pdev)
{
    int err;

    err = gpio_request(S5PV210_GPD0(3), "GPD0");

    if (err) {
        printk(KERN_ERR "failed to request GPD0 for "
            "lcd backlight control\n");
        return err;
    }

    gpio_direction_output(S5PV210_GPD0(3), 1);

    s3c_gpio_cfgpin(S5PV210_GPD0(3), S5PV210_GPD_0_3_TOUT_3);

    gpio_free(S5PV210_GPD0(3));
    return 0;
}

static int lcd_backlight_off(struct platform_device *pdev, int onoff)
{
    int err;

    err = gpio_request(S5PV210_GPD0(3), "GPD0");

    if (err) {
        printk(KERN_ERR "failed to request GPD0 for "
                "lcd backlight control\n");
        return err;
    }

    gpio_direction_output(S5PV210_GPD0(3), 0);
    gpio_free(S5PV210_GPD0(3));
    return 0;
}

static int lcd_reset_lcd(struct platform_device *pdev)
{
    int err;

    err = gpio_request(S5PV210_GPH0(6), "GPH0");
    if (err) {
        printk(KERN_ERR "failed to request GPH0 for "
                "lcd reset control\n");
        return err;
    }

    gpio_direction_output(S5PV210_GPH0(6), 1);
    mdelay(100);

    gpio_set_value(S5PV210_GPH0(6), 0);
    mdelay(10);

    gpio_set_value(S5PV210_GPH0(6), 1);
    mdelay(10);

    gpio_free(S5PV210_GPH0(6));

    return 0;
}

static struct s3c_platform_fb lte480wv_fb_data __initdata = {
    .hw_ver    = 0x62,
    .nr_wins = 5,
    .default_win = CONFIG_FB_S3C_DEFAULT_WINDOW,
    .swap = FB_SWAP_WORD | FB_SWAP_HWORD,
       .lcd = &wvga_s70,
    .cfg_gpio    = lcd_cfg_gpio,
    .backlight_on    = lcd_backlight_on,
    .backlight_onoff    = lcd_backlight_off,
    .reset_lcd    = lcd_reset_lcd,
};
#endif

第二步：使用make menuconfig，去配置当前显示的windows，请配置为windows0

Device Drivers
　　-->Graphics support
   　　--> Support for frame buffer devices
      　　--> (2)     Default Window (0-4) 

修改为

Device Drivers
　　-->Graphics support
    　 --> Support for frame buffer devices
       　　--> (0)     Default Window (0-4)