最近拿到一块开发版，打算在lvds上做些小修改，之前也接触过一点驱动，但是现在的驱动框架看起来和之前的有点差异。
关于lcd的参数信息请参考这篇文章 http://blog.csdn.net/longxiaowu/article/details/24319933
lvds的驱动在framebuffer驱动之下，也就是上层应用只知道有个framebuffer设备也就是dev/fb，而至于下面的显示输出用vga也好hdmi也好还是lvds也好是不关心的。
lvds驱动干的事也挺简单，就是把fb_info这个机构体填充好而已，但是现在并没有在驱动中直接搞一个fb_info的结构体而是在framebuffer驱动中已经申请好了，ldb.c中拿过来
填充一下而已。
代码如下
static int ldb_disp_init(struct mxc_dispdrv_handle *disp, struct mxc_dispdrv_setting *setting) //这个setting中有个fb_info结构体 { int ret = 0, i; struct ldb_data *ldb = mxc_dispdrv_getdata(disp); //lvds自身的结构体 struct fsl_mxc_ldb_platform_data *plat_data = ldb->pdev->dev.platform_data; struct resource *res; uint32_t base_addr; uint32_t reg, setting_idx; uint32_t ch_mask = 0, ch_val = 0; uint32_t ipu_id, disp_id; /* if input format not valid, make RGB666 as default*/ if (!valid_mode(setting->if_fmt)) { dev_warn(&ldb->pdev->dev, "Input pixel format not valid" " use default RGB666\n"); setting->if_fmt = IPU_PIX_FMT_RGB666; } if (!ldb->inited) { char di_clk[] = "ipu1_di0_clk"; char ldb_clk[] = "ldb_di0_clk"; int lvds_channel = 0; setting_idx = 0; res = platform_get_resource(ldb->pdev, IORESOURCE_MEM, 0); //用来获取设备的各种参数比如基地址 if (IS_ERR(res)) return -ENOMEM; base_addr = res->start; ldb->reg = ioremap(base_addr, res->end - res->start + 1); ldb->control_reg = ldb->reg + 2; ldb->gpr3_reg = ldb->reg + 3; ldb->lvds_bg_reg = regulator_get(&ldb->pdev->dev, plat_data->lvds_bg_reg); if (!IS_ERR(ldb->lvds_bg_reg)) { regulator_set_voltage(ldb->lvds_bg_reg, 2500000, 2500000); regulator_enable(ldb->lvds_bg_reg); } /* ipu selected by platform data setting */ setting->dev_id = plat_data->ipu_id; reg = readl(ldb->control_reg); /* refrence resistor select */ reg &= ~LDB_BGREF_RMODE_MASK; if (plat_data->ext_ref) reg |= LDB_BGREF_RMODE_EXT; else reg |= LDB_BGREF_RMODE_INT; /* TODO: now only use SPWG data mapping for both channel */ reg &= ~(LDB_BIT_MAP_CH0_MASK | LDB_BIT_MAP_CH1_MASK); reg |= LDB_BIT_MAP_CH0_SPWG | LDB_BIT_MAP_CH1_SPWG; /* channel mode setting */ reg &= ~(LDB_CH0_MODE_MASK | LDB_CH1_MODE_MASK); reg &= ~(LDB_DATA_WIDTH_CH0_MASK | LDB_DATA_WIDTH_CH1_MASK); if (bits_per_pixel(setting->if_fmt) == 24) reg |= LDB_DATA_WIDTH_CH0_24 | LDB_DATA_WIDTH_CH1_24; else reg |= LDB_DATA_WIDTH_CH0_18 | LDB_DATA_WIDTH_CH1_18; if (g_ldb_mode) ldb->mode = g_ldb_mode; else ldb->mode = plat_data->mode; if ((ldb->mode == LDB_SIN0) || (ldb->mode == LDB_SIN1)) { ret = ldb->mode - LDB_SIN0; if (plat_data->disp_id != ret) { dev_warn(&ldb->pdev->dev, "change IPU DI%d to IPU DI%d for LDB " "channel%d.\n", plat_data->disp_id, ret, ret); plat_data->disp_id = ret; } } else if (((ldb->mode == LDB_SEP0) || (ldb->mode == LDB_SEP1)) && (cpu_is_mx6q() || cpu_is_mx6dl())) { if (plat_data->disp_id == plat_data->sec_disp_id) { dev_err(&ldb->pdev->dev, "For LVDS separate mode," "two DIs should be different!\n"); return -EINVAL; } if (((!plat_data->disp_id) && (ldb->mode == LDB_SEP1)) || ((plat_data->disp_id) && (ldb->mode == LDB_SEP0))) { dev_dbg(&ldb->pdev->dev, "LVDS separate mode:" "swap DI configuration!\n"); ipu_id = plat_data->ipu_id; disp_id = plat_data->disp_id; plat_data->ipu_id = plat_data->sec_ipu_id; plat_data->disp_id = plat_data->sec_disp_id; plat_data->sec_ipu_id = ipu_id; plat_data->sec_disp_id = disp_id; } } if (ldb->mode == LDB_SPL_DI0) { reg |= LDB_SPLIT_MODE_EN | LDB_CH0_MODE_EN_TO_DI0 | LDB_CH1_MODE_EN_TO_DI0; setting->disp_id = 0; } else if (ldb->mode == LDB_SPL_DI1) { reg |= LDB_SPLIT_MODE_EN | LDB_CH0_MODE_EN_TO_DI1 | LDB_CH1_MODE_EN_TO_DI1; setting->disp_id = 1; } else if (ldb->mode == LDB_DUL_DI0) { reg &= ~LDB_SPLIT_MODE_EN; reg |= LDB_CH0_MODE_EN_TO_DI0 | LDB_CH1_MODE_EN_TO_DI0; setting->disp_id = 0; } else if (ldb->mode == LDB_DUL_DI1) { reg &= ~LDB_SPLIT_MODE_EN; reg |= LDB_CH0_MODE_EN_TO_DI1 | LDB_CH1_MODE_EN_TO_DI1; setting->disp_id = 1; } else if (ldb->mode == LDB_SIN0) { reg &= ~LDB_SPLIT_MODE_EN; setting->disp_id = plat_data->disp_id; if (setting->disp_id == 0) reg |= LDB_CH0_MODE_EN_TO_DI0; else reg |= LDB_CH0_MODE_EN_TO_DI1; ch_mask = LDB_CH0_MODE_MASK; ch_val = reg & LDB_CH0_MODE_MASK; } else if (ldb->mode == LDB_SIN1) { reg &= ~LDB_SPLIT_MODE_EN; setting->disp_id = plat_data->disp_id; if (setting->disp_id == 0) reg |= LDB_CH1_MODE_EN_TO_DI0; else reg |= LDB_CH1_MODE_EN_TO_DI1; ch_mask = LDB_CH1_MODE_MASK; ch_val = reg & LDB_CH1_MODE_MASK; } else { /* separate mode*/ setting->disp_id = plat_data->disp_id; /* first output is LVDS0 or LVDS1 */ if (ldb->mode == LDB_SEP0) lvds_channel = 0; else lvds_channel = 1; reg &= ~LDB_SPLIT_MODE_EN; if ((lvds_channel == 0) && (setting->disp_id == 0)) reg |= LDB_CH0_MODE_EN_TO_DI0; else if ((lvds_channel == 0) && (setting->disp_id == 1)) reg |= LDB_CH0_MODE_EN_TO_DI1; else if ((lvds_channel == 1) && (setting->disp_id == 0)) reg |= LDB_CH1_MODE_EN_TO_DI0; else reg |= LDB_CH1_MODE_EN_TO_DI1; ch_mask = lvds_channel ? LDB_CH1_MODE_MASK : LDB_CH0_MODE_MASK; ch_val = reg & ch_mask; if (bits_per_pixel(setting->if_fmt) == 24) { if (lvds_channel == 0) reg &= ~LDB_DATA_WIDTH_CH1_24; else reg &= ~LDB_DATA_WIDTH_CH0_24; } else { if (lvds_channel == 0) reg &= ~LDB_DATA_WIDTH_CH1_18; else reg &= ~LDB_DATA_WIDTH_CH0_18; } } writel(reg, ldb->control_reg); if (ldb->mode < LDB_SIN0) { ch_mask = LDB_CH0_MODE_MASK | LDB_CH1_MODE_MASK; ch_val = reg & (LDB_CH0_MODE_MASK | LDB_CH1_MODE_MASK); } /* clock setting */ if ((cpu_is_mx6q() || cpu_is_mx6dl()) && ((ldb->mode == LDB_SEP0) || (ldb->mode == LDB_SEP1))) ldb_clk[6] += lvds_channel; else ldb_clk[6] += setting->disp_id; ldb->setting[setting_idx].ldb_di_clk = clk_get(&ldb->pdev->dev, ldb_clk); if (IS_ERR(ldb->setting[setting_idx].ldb_di_clk)) { dev_err(&ldb->pdev->dev, "get ldb clk0 failed\n"); iounmap(ldb->reg); return PTR_ERR(ldb->setting[setting_idx].ldb_di_clk); } di_clk[3] += setting->dev_id; di_clk[7] += setting->disp_id; ldb->setting[setting_idx].di_clk = clk_get(&ldb->pdev->dev, di_clk); if (IS_ERR(ldb->setting[setting_idx].di_clk)) { dev_err(&ldb->pdev->dev, "get di clk0 failed\n"); iounmap(ldb->reg); return PTR_ERR(ldb->setting[setting_idx].di_clk); } dev_dbg(&ldb->pdev->dev, "ldb_clk to di clk: %s -> %s\n", ldb_clk, di_clk); /* fb notifier for clk setting */ ldb->nb.notifier_call = ldb_fb_event, ret = fb_register_client(&ldb->nb); if (ret < 0) { iounmap(ldb->reg); return ret; } ldb->inited = true; } //在此之前都是设置一些register的参数而已 ldb->setting[setting_idx].ch_mask = ch_mask; ldb->setting[setting_idx].ch_val = ch_val; if (cpu_is_mx6q() || cpu_is_mx6dl()) ldb_ipu_ldb_route(setting->dev_id, setting->disp_id, ldb); /* * ldb_di0_clk -> ipux_di0_clk * ldb_di1_clk -> ipux_di1_clk */ clk_set_parent(ldb->setting[setting_idx].di_clk, ldb->setting[setting_idx].ldb_di_clk); /* must use spec video mode defined by driver */ ret = fb_find_mode(&setting->fbi->var, setting->fbi, setting->dft_mode_str, ldb_modedb, ldb_modedb_sz, NULL, setting->default_bpp); //填充fb_videomode,填充fb_var_screeninfo if (ret != 1) fb_videomode_to_var(&setting->fbi->var, &ldb_modedb[0]); INIT_LIST_HEAD(&setting->fbi->modelist); for (i = 0; i < ldb_modedb_sz; i++) { struct fb_videomode m; fb_var_to_videomode(&m, &setting->fbi->var); if (fb_mode_is_equal(&m, &ldb_modedb[i])) { fb_add_videomode(&ldb_modedb[i], &setting->fbi->modelist); //把选中的mode加入到list中去 break; } } /* save current ldb setting for fb notifier */ ldb->setting[setting_idx].active = true; ldb->setting[setting_idx].ipu = setting->dev_id; ldb->setting[setting_idx].di = setting->disp_id; return ret; } 到此结束，一个fb_fix_screeninfo没有看到在哪里被赋值，还有就是没有看到framebuffer_register其实framebuffer_register是在mxc_ipuv3_fb.c中
fbi = mxcfb_init_fbinfo(&pdev->dev, &mxcfb_ops); //初始化fb_info结构体, 其中fb->var.active为FB_ACTIVATE_NOW
ret = mxcfb_option_setup(pdev, fbi); //从cmdline获取fb设置，如果没有，就默认使用board中tek_fb_data里的值。
fb_get_options //拿之前video=mxcfb0获取的值和mxcfbx做比较，如果相匹配，然后在解析对应后面的参数。x是当前对应的fb number号，所以这样就会一一对应。如果后面带:off字样，表示不使用此路通道。
ret = mxcfb_dispdrv_init(pdev, fbi);就是这里调用了ldb.c里的init
mxc_dispdrv_gethandle -> //根据传进来的disp_dev name在dispdrv_list中匹配获取对应的driver handle,这里是获取的是ldb的handle，它的注册是在ldb_probe()的mxc_dispdrv_register实现的，它将自己添加到了dispdrv_list。
entry->drv->init -> //mxc_dispdrv.c 调用对应driver的init函数，这里就是ldb driver对应的init了。 ldb_disp_init -> ldb.c fb_find_mode //寻找最合适的LCD参数 mxcfb_register ->
register_framebuffer //注册fb
所有现在的架构就是和以前不一样了