原文:http://www.arm9home.net/read.php?tid-25938.html

管理提醒：?本帖被 xoom 執(zhí)行加亮操作(2012-12-13)
如之前所說，一直想知道顯示數(shù)據(jù)都在哪個(gè)地方，通常的數(shù)據(jù)，比如 framebuffer 中的顯示數(shù)據(jù)，和OpenGL 處理的數(shù)據(jù)有啥關(guān)系。
目前為止我還沒有弄明白 OpenGL 這塊，但是 framebuffer 這部分差不多了。這篇文章記錄了 framebuffer 的顯示數(shù)據(jù)相關(guān)內(nèi)容。

1. 關(guān)于FIMD

????Tiny210v2 開發(fā)板屬于 s5pv210 的一種，在這塊開發(fā)板上，顯示部分又被叫做 FIMD，我不知道FIMD是什么的縮寫，但D應(yīng)該和Display Controller有關(guān)系吧。
????FIMD 的主要功能就是獲取顯示數(shù)據(jù)，并將數(shù)據(jù)輸出到顯示屏。當(dāng)然期間會(huì)對(duì)顯示數(shù)據(jù)進(jìn)行處理：

?????????
?

????FIMD一共支持5個(gè)layer，在SoC用戶手冊(cè)中，將layer成為window，源代碼中也叫做window。

?????????
?

????FIMD可以通過AXI總線從內(nèi)存或者Camera哪里獲取到顯示數(shù)據(jù)，并進(jìn)行合成。

?????????
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????
2. 內(nèi)核配置 framebuffer

????通過 make menuconfig 可以配置 framebuffer 相關(guān)的內(nèi)容。
????
?????????
?

????保存以后，在 .config 文件中可以找到相關(guān)配置內(nèi)容。
????
????????.config
????????--------------------------------------------------

復(fù)制代碼 ????????CONFIG_FB_S3C_DEFAULT_WINDOW=2 ????????CONFIG_FB_S3C_NR_BUFFERS=3 ????????CONFIG_FB_S3C_NUM_OVLY_WIN=1 ????????CONFIG_FB_S3C_NUM_BUF_OVLY_WIN=3

????同樣也會(huì)在頭文件中生成宏定義：

????????include/generated/autoconf.h
????????--------------------------------------------------

復(fù)制代碼 ????????#define CONFIG_FB_S3C_DEFAULT_WINDOW 2 ????????#define CONFIG_FB_S3C_NR_BUFFERS 3 ????????#define CONFIG_FB_S3C_NUM_OVLY_WIN 1 ????????#define CONFIG_FB_S3C_NUM_BUF_OVLY_WIN 3

????
????CONFIG_FB_S3C_DEFAULT_WINDOW 是指 默認(rèn)的 window， 0-4。
????CONFIG_FB_S3C_NR_BUFFERS 是指 window 的buffer數(shù)，3個(gè)就是 trebble-buffer，2個(gè)就是double-buffer。
????其中第一個(gè)是正在顯示的數(shù)據(jù)，又叫onscreen，其他幾個(gè)是后臺(tái)描畫的數(shù)據(jù)，又叫offscreen，通過 flip 操作可以將 onscreen 數(shù)據(jù)和offscreen 數(shù)據(jù)交換。
????CONFIG_FB_S3C_NUM_OVLY_WIN 是 OVERLAY window， 0-4。
????CONFIG_FB_S3C_NUM_BUF_OVLY_WIN 是指 OVERLAY window 的buffer數(shù)，和 CONFIG_FB_S3C_NR_BUFFERS 一個(gè)意思。
????????
3. 顯示數(shù)據(jù)buffer

????內(nèi)核初始話過程中，為這些window 的 buffer 預(yù)留了一部分內(nèi)存。
????具體看下面的代碼：

????初始化函數(shù)會(huì)首先映射內(nèi)存空間：
????????

復(fù)制代碼 ????????MACHINE_START(MINI210, "MINI210") ????????????/* Maintainer: Kukjin Kim <kgene.kim@samsung.com> */ ????????????.boot_params????= S5P_PA_SDRAM + 0x100, ????????????.fixup????????????= mini210_fixup, ????????????.init_irq????????= s5pv210_init_irq, ????????????.map_io????????????= mini210_map_io, ????????????.init_machine????= mini210_machine_init, ????????#ifdef CONFIG_S5P_HIGH_RES_TIMERS ????????????.timer????????????= &s5p_systimer, ????????#else ????????????.timer????????????= &s5p_timer, ????????#endif ????????MACHINE_END

????
????在映射內(nèi)存空間中，保留了一部分內(nèi)存，保留的大小就和window 以及 buffer數(shù)有關(guān)系：
????大小是 800 x 480 x 2個(gè)window x 3個(gè)buffer x RGBA的4字節(jié),這是給通常顯示數(shù)據(jù)的，
????除此之外，還預(yù)留了 YUV 的數(shù)據(jù)區(qū)域，1280 x 720 x 3個(gè)buffer x Y的一個(gè)字節(jié)數(shù)據(jù) + 1280 x 720 x 3個(gè)buffer x UV的一個(gè)字節(jié)數(shù)據(jù)。
????另外還有一個(gè) 4096 字節(jié)大小的 數(shù)據(jù)。

????這些數(shù)據(jù)我只理解了 RGBA 數(shù)據(jù)， YUV 的數(shù)據(jù)不知道是干啥的？ 難道是給 HDMI 輸出用的？
????????
????????arch/arm/mach-sp5v210/Mach-mini210.c
????????--------------------------------------------------

復(fù)制代碼 ????????/* Multimedia support */ ????????#define LCD_WIDTH????????????????800 ????????#define LCD_HEIGHT????????????????480 ????????#define BYTES_PER_PIXEL????????????4 ????????#define NUM_BUFFER_OVLY????????????(CONFIG_FB_S3C_NUM_OVLY_WIN * CONFIG_FB_S3C_NUM_BUF_OVLY_WIN) ????????#define NUM_BUFFER????????????????(CONFIG_FB_S3C_NR_BUFFERS + NUM_BUFFER_OVLY) ????????#define PXL2FIMD(pixels)????????((pixels) * BYTES_PER_PIXEL * NUM_BUFFER) ????????#define S5PV210_VIDEO_SAMSUNG_MEMSIZE_FIMD????????PXL2FIMD(LCD_WIDTH * LCD_HEIGHT) ???????? ????????static struct s5p_media_device mini210_media_devs[] = { ????????????......, ????????????{ ????????????????.id????????????= S5P_MDEV_FIMD, ????????????????.name????????= "fimd", ????????????????.bank????????= 1, ????????????????.memsize????= S5PV210_VIDEO_SAMSUNG_MEMSIZE_FIMD, ????????????????.paddr????????= 0, ????????????}, ????????????......, ????????} ????????static void __init mini210_map_io(void) ????????{ ????????????...... ????????????frame_size = lcd->width * lcd->height * BYTES_PER_PIXEL; ????????????fimd_size = ALIGN(frame_size, PAGE_SIZE) * NUM_BUFFER; ????????????if (frame_size > 0x200000) { ????????????????fimd_size += ALIGN(frame_size, PAGE_SIZE) * 2;????????????// Not used ????????????} ????????????/* Reserve 0x003f6000 bytes for PVR YUV video, and 1 page */ ????????????fimd_size += ALIGN(1280*720, PAGE_SIZE) * 3; ????????????fimd_size += ALIGN(1280*360, PAGE_SIZE) * 3 + PAGE_SIZE; ????????????if (fimd_size != S5PV210_VIDEO_SAMSUNG_MEMSIZE_FIMD) { ????????????????mini210_fixup_bootmem(S5P_MDEV_FIMD, fimd_size); ????????????} ????????????...... ????????????s5p_reserve_bootmem(mini210_media_devs, ARRAY_SIZE(mini210_media_devs), S5P_RANGE_MFC); ????????????...... ????????}

????這些內(nèi)存是PAGE對(duì)齊的，對(duì)齊的部分參考下面的算法。
????PAGE_SIZE 大小是 4096。

????????include/linux/Const.h
????????--------------------------------------------------

復(fù)制代碼 ????????#ifdef __ASSEMBLY__ ????????#define _AC(X,Y)????X ????????#define _AT(T,X)????X ????????#else ????????#define __AC(X,Y)????(X##Y) ????????#define _AC(X,Y)????__AC(X,Y) ????????#define _AT(T,X)????((T)(X)) ????????#endif

????????
????????arch/arm/include/asm/Page.h
????????--------------------------------------------------

復(fù)制代碼 ????????#define PAGE_SHIFT????????12 ????????#define PAGE_SIZE????????(_AC(1,UL) << PAGE_SHIFT)

????????
????????include/linux/Kernel.h
????????--------------------------------------------------

復(fù)制代碼 ????????#define __ALIGN_KERNEL_MASK(x, mask)????(((x) + (mask)) & ~(mask)) ????????#define __ALIGN_KERNEL(x, a)????????__ALIGN_KERNEL_MASK(x, (typeof(x))(a) - 1) ????????#define ALIGN(x, a)????????__ALIGN_KERNEL((x), (a))

????????

4. 內(nèi)核關(guān)于FIMD內(nèi)存預(yù)留的相關(guān)debug log

????在內(nèi)核的 boot log 中，我們可以找到關(guān)于內(nèi)存預(yù)留的log：

????????dmesg log :
????????--------------------------------------------------
????????[????0.000000] s5p: 13060 kbytes system memory reserved for fimd at 0x3c330000, 1-bank base(0x3c330000)?
????????
????????[????0.648804] fimd at 0x3c330000



5. 物理內(nèi)存視圖

????畫了一個(gè)簡(jiǎn)單的物理內(nèi)存布局圖，可以看到 RGBA 部分的數(shù)據(jù)，其實(shí)一共給 2 個(gè) window 預(yù)留了。

????????|??????????????|
????????|--------------|
????????|??????????????|0x3CFF0000 -- 0x3CFF0FFF || ????
????????|--------------|
????????|??????????????|0x3CF7F000 -- 0x3CFEFFFF ||
????????|--------------|???????????????????????? ||
????????|??????????????|0x3CF0E000 -- 0x3CF7EFFF || treble-buffer YUV( UV ) framebuffer : 1280 x 360 x 1 byte
????????|--------------|???????????????????????? ||
????????|??????????????|0x3CE9D000 -- 0x3CF0DFFF ||
????????|--------------|???????????????????????????
????????|??????????????|0x3CDBC000 -- 0x3CE9EFFF ||
????????|--------------|???????????????????????? ||
????????|??????????????|0x3CCDB000 -- 0x3CDBBFFF || treble-buffer YUV(??Y ) framebuffer : 1280 x 720 x 1 byte
????????|--------------|???????????????????????? ||
????????|??????????????|0x3CBFA000 -- 0x3CCDAFFF ||
????????|--------------|???????????????????????????
????????|??????????????|0x3CA83000 -- 0x3CBF9FFF ||
????????|--------------|???????????????????????? ||
????????|??????????????|0x3C90C000 -- 0x3CA82FFF || treble-buffer RGBA framebuffer : 800 x 480 x 4 bytes
????????|--------------|???????????????????????? ||
????????|??????????????|0x3C795000 -- 0x3C90BFFF ||
????????|--------------|???????????????????????????
????????|??????????????|0x3C61E000 -- 0x3C794FFF ||
????????|--------------|???????????????????????? ||
????????|??????????????|0x3C4A7000 -- 0x3C61DFFF || treble-buffer RGBA framebuffer : 800 x 480 x 4 byte
????????|--------------|???????????????????????? ||
????????|??????????????|0x3C330000 -- 0x3C4A6FFF ||
????????|--------------|
????????|??????????????|

6. 將預(yù)留的物理內(nèi)存記錄到platform信息中

????這些預(yù)留的物理內(nèi)存，在 platform 初始化過程中，會(huì)映射到內(nèi)存空間。
????在開發(fā)板初始化過程中，會(huì)進(jìn)行 machine init, 而 machine init 過程中會(huì)調(diào)用 s3c_fb_set_platdata 初始化 platform 信息。
????????
????????arch/arm/mach-sp5v210/Mach-mini210.c
????????--------------------------------------------------

復(fù)制代碼 ????????static struct s3c_platform_fb mini210_fb_data __initdata = { ????????????.hw_ver????????????= 0x62, ????????????.clk_name?????? = "sclk_fimd", ????????????.nr_wins????????= 5, ????????????.default_win????= CONFIG_FB_S3C_DEFAULT_WINDOW, ????????????.swap????????????= FB_SWAP_WORD | FB_SWAP_HWORD, ???????? ????????????.cfg_gpio????????= lcd_cfg_gpio, ????????????.backlight_on????= lcd_backlight_on, ????????????.backlight_onoff= lcd_backlight_off, ????????????.reset_lcd????????= lcd_reset_lcd, ????????}; ????????static void __init mini210_machine_init(void) ????????{ ????????????...... ????????#ifdef CONFIG_FB_S3C_MINI210 ????????????{ ????????????????struct s3cfb_lcd *mlcd = mini210_get_lcd(); ????????????????if (!(mlcd->args & 0x0f)) { ????????????????????if (readl(S5PV210_GPF0_BASE + 0x184) & 0x10) ????????????????????????mlcd->args |= (1 << 7); ????????????????} ????????????????mini210_fb_data.lcd = mlcd; ????????????????s3c_fb_set_platdata(&mini210_fb_data); ????????????} ????????#endif ????????????...... ????????} ???????? ????????MACHINE_START(MINI210, "MINI210") ????????????/* Maintainer: Kukjin Kim <kgene.kim@samsung.com> */ ????????????.boot_params????= S5P_PA_SDRAM + 0x100, ????????????.fixup????????????= mini210_fixup, ????????????.init_irq????????= s5pv210_init_irq, ????????????.map_io????????????= mini210_map_io, ????????????.init_machine????= mini210_machine_init, ????????#ifdef CONFIG_S5P_HIGH_RES_TIMERS ????????????.timer????????????= &s5p_systimer, ????????#else ????????????.timer????????????= &s5p_timer, ????????#endif ????????MACHINE_END

????
????在platform初始化過程中，就會(huì)通過 pmem_start 和 pmem_size 分別記錄這5個(gè)window 的物理內(nèi)存地址和大小。????
????注意的是 platform 初始化，相當(dāng)于是記錄系統(tǒng)都有哪些資源。而設(shè)備驅(qū)動(dòng)初始化過程中，比如s3cfb這個(gè)fb驅(qū)動(dòng)，則會(huì)來使用這些資源。

????????arch/arm/plat-s5p/include/plat/Fb.h
????????--------------------------------------------------

復(fù)制代碼 ????????struct s3c_platform_fb { ????????????int????????????hw_ver; ????????????char????????clk_name[16]; ????????????int????????????nr_wins; ????????????int????????????nr_buffers[5]; ????????????int????????????default_win; ????????????int????????????swap; ????????????phys_addr_t????pmem_start[5]; /* starting physical address of memory region */ ????????????size_t????????pmem_size[5]; /* size of memory region */ ????????????void????????*lcd; ????????????void????????(*cfg_gpio)(struct platform_device *dev); ????????????int????????????(*backlight_on)(struct platform_device *dev); ????????????int????????????(*backlight_onoff)(struct platform_device *dev, int onoff); ????????????int????????????(*reset_lcd)(struct platform_device *dev); ????????????int????????????(*clk_on)(struct platform_device *pdev, struct clk **s3cfb_clk); ????????????int????????????(*clk_off)(struct platform_device *pdev, struct clk **clk); ????????};

????????
????????arch/arm/plat-samsung/Dev-fb.c
????????--------------------------------------------------

復(fù)制代碼 ?????? void __init s3c_fb_set_platdata(struct s3c_platform_fb *pd) ????????{ ????????????struct s3c_platform_fb *npd; ????????????struct s3cfb_lcd *lcd; ????????????phys_addr_t pmem_start; ????????????int i, default_win, num_overlay_win; ????????????int frame_size; ???????? ????????????if (!pd) ????????????????pd = &default_fb_data; ???????? ????????????npd = kmemdup(pd, sizeof(struct s3c_platform_fb), GFP_KERNEL); ????????????if (!npd) { ????????????????printk(KERN_ERR "%s: no memory for platform data\n", __func__); ???????? ????????????} else { ????????????????for (i = 0; i < npd->nr_wins && i < NR_BUFFERS; i++) { ????????????????????npd->nr_buffers?? = 1; ????????????????} ???????? ????????????????default_win = npd->default_win; ????????????????num_overlay_win = CONFIG_FB_S3C_NUM_OVLY_WIN; ????????????????if (num_overlay_win >= default_win) { ????????????????????printk(KERN_WARNING "%s: NUM_OVLY_WIN should be less than default \ ????????????????????????????window number. set to 0.\n", __func__); ????????????????????num_overlay_win = 0; ????????????????} ????????????????...... ???????????????? ????????????????/* set starting physical address & size of memory region for ???????????????? * overlay window and default window */ ????????????????pmem_start = s5p_get_media_memory_bank(S5P_MDEV_FIMD, 1); ????????????????printk("fimd at 0x%08x\n", pmem_start); ???????? ????????????????for (i = 0; i < num_overlay_win; i++) { ????????????????????*(npd->nr_buffers+i) = CONFIG_FB_S3C_NUM_BUF_OVLY_WIN; ????????????????????*(npd->pmem_start+i) = pmem_start; ????????????????????*(npd->pmem_size+i) = frame_size *?? *(npd->nr_buffers+i); ????????????????????pmem_start += *(npd->pmem_size+i); ????????????????} ???????? ????????????????npd->nr_buffers[default_win] = CONFIG_FB_S3C_NR_BUFFERS; ????????????????npd->pmem_start[default_win] = pmem_start; ????????????????npd->pmem_size[default_win] = frame_size * npd->nr_buffers[default_win]; ???????? ????????#if defined(CONFIG_MACH_MINI210) ????????????????npd->pmem_size[default_win] += ALIGN(1280*720, PAGE_SIZE) * 3; ????????????????npd->pmem_size[default_win] += ALIGN(1280*360, PAGE_SIZE) * 3 + PAGE_SIZE; ???????? ????????????????if (frame_size > 0x200000) {????????????????????????????????????????// Not Used : frame_size < 0x200000 ????????????????????pmem_start += npd->pmem_size[default_win]; ????????????????????for (; i < npd->nr_wins; i++) { ????????????????????????if (i != default_win) { ????????????????????????????npd->nr_buffers[i] = 2; ????????????????????????????npd->pmem_start[i] = pmem_start; ????????????????????????????npd->pmem_size[i] = frame_size * npd->nr_buffers[i]; ????????????????????????????break; ????????????????????????} ????????????????????} ????????????????} ????????#endif ???????? ????????????????s3c_device_fb.dev.platform_data = npd; ????????????} ????????}

????
????我們需要留意一下上面這段代碼，????
????因?yàn)?num_overlay_win 是 CONFIG_FB_S3C_NUM_OVLY_WIN=1,所以 for 循環(huán)只執(zhí)行了一次，那么 window 0 的物理內(nèi)存地址初始化了。
????然后又手工為 default_win 也就是 CONFIG_FB_S3C_DEFAULT_WINDOW=2 進(jìn)行了初始化。
????也就是說： window 0 和 window 2 在platform初始化中記錄了數(shù)據(jù)buffer的物理內(nèi)存地址。
????雖然是 for 循環(huán)做的，我認(rèn)為這個(gè)for循環(huán)寫得不好。


7. 在s3cfb初始化過程中,為window 關(guān)聯(lián)這些內(nèi)存

????在初始化過程中，會(huì)分配fb設(shè)備相關(guān)數(shù)據(jù)結(jié)構(gòu)，并注冊(cè)fb設(shè)備。

????????drivers/video/samsung/s3cfb.c
????????--------------------------------------------------

復(fù)制代碼 ????????static int __devinit s3cfb_probe(struct platform_device *pdev) ????????{ ????????????...... ????????????if (s3cfb_alloc_framebuffer(fbdev)) { ????????????????ret = -ENOMEM; ????????????????goto err_alloc; ????????????} ???????? ????????????if (s3cfb_register_framebuffer(fbdev)) { ????????????????ret = -EINVAL; ????????????????goto err_register; ????????????} ????????????...... ????????}

????但是我們發(fā)現(xiàn)，只有當(dāng) fb 設(shè)備對(duì)應(yīng)的 window 是 default window ，也就是 window 2 的時(shí)候，
????才會(huì)將 window 2 對(duì)應(yīng)的內(nèi)存映射到內(nèi)存空間。
????雖然預(yù)留的物理內(nèi)存是 window 0 和 window 2 的，但這個(gè)時(shí)候 window 0 的物理內(nèi)存是沒有被映射的。

????????drivers/video/samsung/s3cfb.c
????????--------------------------------------------------

復(fù)制代碼 ????????static int s3cfb_alloc_framebuffer(struct s3cfb_global *ctrl) ????????{ ????????????...... ????????????for (i = 0; i < pdata->nr_wins; i++) { ????????????????ctrl->fb[i] = framebuffer_alloc(sizeof(*ctrl->fb), ctrl->dev); ????????????????if (!ctrl->fb[i]) { ????????????????????dev_err(ctrl->dev, "not enough memory\n"); ????????????????????ret = -ENOMEM; ????????????????????goto err_alloc_fb; ????????????????} ????????????????...... ????????????????if (i == pdata->default_win) { ????????????????????if (s3cfb_map_video_memory(ctrl->fb[i])) { ????????????????????????dev_err(ctrl->dev, ????????????????????????????"failed to map video memory " ????????????????????????????"for default window (%d)\n", i); ????????????????????????ret = -ENOMEM; ????????????????????????goto err_map_video_mem; ????????????????????} ????????????????} ????????????} ????????????...... ????????}

????
????這是注冊(cè) fb 設(shè)備的地方，只要注冊(cè)成功，/dev 目錄下就會(huì)有一個(gè) fb 文件。
????雖然只給 window 2 映射了顯示數(shù)據(jù)的內(nèi)存，但是 for 循環(huán)還是將所有的 window 都注冊(cè)設(shè)備文件了。
????這就是為什么 /dev 目錄下有 fb0 - fb4 5個(gè)fb設(shè)備。其實(shí)每一個(gè) fb 設(shè)備對(duì)應(yīng)一個(gè) window。
????
????另外需要注意的是，第一個(gè)注冊(cè)的 fb 是 fb0，然后依次 ++。
????下面的代碼在注冊(cè)的時(shí)候， 首先注冊(cè)的是 default window 2，然后是 3, 4, 0, 1。
????也就是說 ：
????fb0 -> window 2
????fb1 -> window 3
????fb2 -> window 4
????fb3 -> window 0
????fb4 -> window 1

????另外還需要注意的是，如果你直接去 cat??/dev/fbX ，只有 fb0 是成功的，其他全部失敗，
????因?yàn)榈侥壳拔恢?#xff0c;只有 fb0 也就是 default window 2，映射了顯示數(shù)據(jù)的內(nèi)存。
????????
????????drivers/video/samsung/s3cfb.c
????????--------------------------------------------------

復(fù)制代碼 ????????static int s3cfb_register_framebuffer(struct s3cfb_global *ctrl) ????????{ ????????????...... ????????????k = 0; ????????????for (i = pdata->default_win; ????????????????i < pdata->nr_wins + pdata->default_win; i++) { ????????????????????j = i % pdata->nr_wins; ????????????????????ret = register_framebuffer(ctrl->fb[j]); ????????????????????if (ret) { ????????????????????????dev_err(ctrl->dev, "failed to register " ????????????????????????????????"framebuffer device\n"); ????????????????????????ret = -EINVAL; ????????????????????????goto err_register_fb; ????????????????????} ????????????????????pdata->fb_file_minor[ j ] = k; ????????????????????k++; ???????????????????? ????????????????????#ifndef CONFIG_FRAMEBUFFER_CONSOLE ????????????????????if (j == pdata->default_win) { ????????????????????????s3cfb_check_var(&ctrl->fb[j]->var, ctrl->fb[j]); ????????????????????????s3cfb_set_par(ctrl->fb[j]); ????????????????????????s3cfb_draw_logo(ctrl->fb[j]); ????????????????????} ????????????????????#endif ????????????} ????????????...... ????????}

8. 內(nèi)核關(guān)于顯示內(nèi)存映射的相關(guān)debug log

????需要注意一下，部分log中寫的是fb2，但這個(gè)log是boot階段的，真正有效的是fb0，
????代碼中l(wèi)og寫錯(cuò)了，fb 很多應(yīng)該是 window。fb0 -> window 2

????????dmesg log :
????????--------------------------------------------------
????????[??507.316250] [s3cfb]win 2: pmem_start=0x3c795000
????????[??507.316292] [s3cfb][fb2] dma: 0x3c795000, cpu: 0xe1000000, size: 0x0085c000
????????
????????[??507.333888] PA FB = 0x3C795000, bits per pixel = 32
????????[??507.333933] screen width=800 height=480 va=0xdc795000 pa=0x3c795000
????????[??507.333987] xres_virtual = 800, yres_virtual = 1440, xoffset = 0, yoffset = 0
????????[??507.336543] fb_size=8765440?
????????[??507.339351] Back frameBuffer[0].VAddr=dc90c000 PAddr=3c90c000 size=1536000?
????????[??507.346146] Back frameBuffer[1].VAddr=dca83000 PAddr=3ca83000 size=1536000?
????????[??507.353014] Video Y Buffer[0].VAddr=dcbfa000 PAddr=3cbfa000 size=921600
????????[??507.359576] Video Y Buffer[1].VAddr=dccdb000 PAddr=3ccdb000 size=921600?
????????[??507.366161] Video Y Buffer[2].VAddr=dcdbc000 PAddr=3cdbc000 size=921600
????????[??507.372750] Video UV Buffer[0].VAddr=dce9d000 PAddr=3ce9d000 size=462848
????????[??507.379418] Video UV Buffer[1].VAddr=dcf0e000 PAddr=3cf0e000 size=462848
????????[??507.386093] Video UV Buffer[2].VAddr=dcf7f000 PAddr=3cf7f000 size=462848


9. 顯示數(shù)據(jù)使用內(nèi)存映射的一些細(xì)節(jié)

????s3cfb_map_video_memory 這個(gè)函數(shù)用于映射顯示數(shù)據(jù)的內(nèi)存地址，
????如果是 platform 初始化過程中預(yù)留過物理內(nèi)存，則會(huì)使用這個(gè)物理內(nèi)存。
????否則就會(huì)臨時(shí)申請(qǐng)一塊內(nèi)存。

????也就是說 window 0 和 window 2 會(huì)使用預(yù)留的物理內(nèi)存。
????window 1 / window 3 / window 4 會(huì)使用新申請(qǐng)的內(nèi)存。

????????drivers/video/samsung/s3cfb.c
????????--------------------------------------------------

復(fù)制代碼 ????????static int s3cfb_map_video_memory(struct fb_info *fb) ????????{ ????????????...... ????????????if (win->owner == DMA_MEM_OTHER) { ????????????????fix->smem_start = win->other_mem_addr; ????????????????fix->smem_len = win->other_mem_size; ????????????????return 0; ????????????} ???????? ????????????if (fb->screen_base) ????????????????return 0; ???????? ????????????if (pdata && pdata->pmem_start[win->id] && (pdata->pmem_size[win->id] >= fix->smem_len)) { ????????????????fix->smem_start = pdata->pmem_start[win->id]; ????????????????fix->smem_len = pdata->pmem_size[win->id]; ????????????????fb->screen_base = ioremap_wc(fix->smem_start, pdata->pmem_size[win->id]); ???????? ????????????????dev_err(fbdev->dev, "[fb%d][win%d]: pmem_start=0x%x\n", ????????????????????????pdata->fb_file_minor[win->id],win->id, pdata->pmem_start[win->id]); ????????????} else { ????????????????fb->screen_base = dma_alloc_writecombine(fbdev->dev, ????????????????????????PAGE_ALIGN(fix->smem_len), ????????????????????????(unsigned int *)&fix->smem_start, GFP_KERNEL); ????????????} ????????????...... ????????}

????除了在初始化的時(shí)候會(huì)映射以外，
????還可一通過 ioctl 來調(diào)用 s3cfb_map_video_memory。
????傳遞的參數(shù)是 FBIOPUT_VSCREENINFO。

????????drivers/video/samsung/s3cfb.c
????????--------------------------------------------------

復(fù)制代碼 ????????static int s3cfb_set_par(struct fb_info *fb) ????????{ ????????????...... ????????????if (win->id != pdata->default_win) { ????????????????fb->fix.line_length = fb->var.xres_virtual * ????????????????????????????????fb->var.bits_per_pixel / 8; ????????????????fb->fix.smem_len = fb->fix.line_length * fb->var.yres_virtual; ???????? ????????????????s3cfb_map_video_memory(fb); ????????????} ????????????...... ????????} ????????struct fb_ops s3cfb_ops = { ????????????.fb_set_par = s3cfb_set_par, ????????}; ????????drivers/video/fbmem.c ????????-------------------------------------------------- ????????int fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var) ????????{ ????????????...... ????????????if (info->fbops->fb_set_par) { ????????????????ret = info->fbops->fb_set_par(info); ????????????????...... ????????????} ????????????...... ????????} ????????static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,unsigned long arg) ????????{ ????????????case FBIOPUT_VSCREENINFO: ????????????????...... ????????????????ret = fb_set_var(info, &var); ????????????????..... ????????????????break; ????????} ????????static long fb_ioctl(struct file *file, unsigned int cmd, unsigned long arg) ????????{ ????????????...... ????????????return do_fb_ioctl(info, cmd, arg); ????????????...... ????????} ????????static const struct file_operations fb_fops = { ????????????...... ????????????.unlocked_ioctl = fb_ioctl, ????????????...... ????????};

10. 在s3cfb初始化過程中映射FIMD的控制寄存器，用于控制硬件

????FIMD的控制寄存器和內(nèi)存是統(tǒng)一編址的，因此可以像使用內(nèi)存一樣訪問他們，但前提是需要將他們映射到內(nèi)存空間。
????內(nèi)核代碼中的寄存器地址定義都能和 SoC 用戶手冊(cè)對(duì)應(yīng)上，我們看看下面的截圖，很一致吧。
????但是在看代碼的過程中，我發(fā)現(xiàn)代碼使用的寄存器的一些信息，Soc 用戶手冊(cè)沒有，是不是用戶手冊(cè)比較老了？
????
?????????
?

?????????
?

????在 s3cfb 模塊初始化的過程中，就會(huì)將控制寄存器映射到內(nèi)存中。

????????arch/arm/mach-sp5v210/include/mach/map.h
????????--------------------------------------------------

復(fù)制代碼 ????????#define S5PV210_PA_LCD??????????(0xF8000000) ????????#define S5P_PA_LCD??????????????S5PV210_PA_LCD ????????#define S5PV210_SZ_LCD??????????SZ_1M ????????#define S5P_SZ_LCD??????????????S5PV210_SZ_LCD

????????
????????
????????arch/arm/plat-samsung/dev-fb.c
????????--------------------------------------------------

復(fù)制代碼 ????????static struct resource s3cfb_resource[] = { ????????????[0] = { ????????????????.start????????= S5P_PA_LCD, ????????????????.end????????= S5P_PA_LCD + S5P_SZ_LCD - 1, ????????????????.flags????????= IORESOURCE_MEM, ????????????}, ????????????[1] = { ????????????????.start????????= IRQ_LCD1, ????????????????.end????????= IRQ_LCD1, ????????????????.flags????????= IORESOURCE_IRQ, ????????????}, ????????????[2] = { ????????????????.start????????= IRQ_LCD0, ????????????????.end????????= IRQ_LCD0, ????????????????.flags????????= IORESOURCE_IRQ, ????????????}, ????????}; ???????? ????????static u64 fb_dma_mask = 0xffffffffUL; ???????? ????????struct platform_device s3c_device_fb = { ????????????.name????????????= "s3cfb", ????????????.id????????????????= -1, ????????????.num_resources????= ARRAY_SIZE(s3cfb_resource), ????????????.resource????????= s3cfb_resource, ????????????.dev????????????= { ????????????????.dma_mask????????????= &fb_dma_mask, ????????????????.coherent_dma_mask????= 0xffffffffUL ????????????} ????????}; ???????? ????????drivers/video/samsung/s3cfb.c ????????-------------------------------------------------- ????????static int __devinit s3cfb_probe(struct platform_device *pdev) ????????{ ????????????...... ????????????res = platform_get_resource(pdev, IORESOURCE_MEM, 0); ????????????if (!res) { ????????????????dev_err(fbdev->dev, "failed to get io memory region\n"); ????????????????ret = -EINVAL; ????????????????goto err_io; ????????????} ???????? ????????????res = request_mem_region(res->start, res->end - res->start + 1, pdev->name); ????????????if (!res) { ????????????????dev_err(fbdev->dev, "failed to request io memory region\n"); ????????????????ret = -EINVAL; ????????????????goto err_io; ????????????} ???????? ????????????fbdev->regs = ioremap(res->start, res->end - res->start + 1); ????????????if (!fbdev->regs) { ????????????????dev_err(fbdev->dev, "failed to remap io region\n"); ????????????????ret = -EINVAL; ????????????????goto err_mem; ????????????} ????????????...... ????????}

????????
????s3cfb_fimd6x.c這個(gè)文件將讀寫 FIMD 的控制寄存器相關(guān)功能都集中在這里了。
????我理解 6x 可能是對(duì)應(yīng)硬件版本號(hào)，因?yàn)橛∠笾锌吹接布姹咎?hào)好象是 0x62。

????通過設(shè)定這些控制寄存器，就能控制比如 window 是否顯示啊，顯示數(shù)據(jù)格式是啥啊，顯示數(shù)據(jù)地址在哪里啊，等等。

????????drivers/video/samsung/s3cfb_fimd6x.c
????????--------------------------------------------------

復(fù)制代碼 ????????int s3cfb_display_on(struct s3cfb_global *ctrl) ????????{ ????????????u32 cfg; ???????? ????????????cfg = readl(ctrl->regs + S3C_VIDCON0); ????????????cfg |= (S3C_VIDCON0_ENVID_ENABLE | S3C_VIDCON0_ENVID_F_ENABLE); ????????????writel(cfg, ctrl->regs + S3C_VIDCON0); ???????? ????????????dev_dbg(ctrl->dev, "global display is on\n"); ???????? ????????????return 0; ????????}

11. 用戶空間的測(cè)試用例

????這個(gè)用例其實(shí)是用來確認(rèn) /dev 目錄下的 fb0 - fb4 是否好用的，以及 window 之間的alpha透過是否正確。

????關(guān)于 window 之間的層次關(guān)系可以參考：
?????????
?

????下面的代碼，大概意思是：
????* 打開 window 0 - window 4 對(duì)應(yīng)的 fb 設(shè)備文件。
????* 設(shè)置這些 window 都是 800 x 480 x RGBA
????* 設(shè)置這些 window 內(nèi)部的顯示數(shù)據(jù)，是從 window 0 - window 4 開始的，分別畫 500x480, 400x480, 300x480, 200x480, 100x480 這么大塊數(shù)據(jù)。
????* 讓window 的顯示數(shù)據(jù)顯示出來。

????????s3cfb_test.c
????????--------------------------------------------------

復(fù)制代碼 ????????#include <sys/types.h> ????????#include <sys/stat.h> ????????#include <sys/ioctl.h> ????????#include <sys/mman.h> ????????#include <fcntl.h> ????????#include <stdio.h> ????????#include <string.h> ????????#include <linux/fb.h> ???????? ???????? ????????#define????WIN0????0 ????????#define????WIN1????1 ????????#define????WIN2????2 ????????#define????WIN3????3 ????????#define????WIN4????4 ????????#define????WIN_MAX????5 ???????? ????????const char * fb_file_path[ WIN_MAX ] = { ????????/* WIN0 */"/dev/fb3", ????????/* WIN1 */"/dev/fb4", ????????/* WIN2 */"/dev/fb0", ????????/* WIN3 */"/dev/fb1", ????????/* WIN4 */"/dev/fb2" ????????}; ????????const int fb_x[ WIN_MAX ] = { ????????/* WIN0 */500, ????????/* WIN1 */400, ????????/* WIN2 */300, ????????/* WIN3 */200, ????????/* WIN4 */100 ????????}; ????????const int fb_color[ WIN_MAX ] = { ????????/* WIN0 */0x10FFFFFF, ????????/* WIN1 */0x10FF0000, ????????/* WIN2 */0x1000FF00, ????????/* WIN3 */0x100000FF, ????????/* WIN4 */0x10000000, ????????}; ???????? ????????void draw_framebuffer( int win, int fd, int xres, int yres ) ????????{ ????????????int i, j; ????????????int *p; ????????????int color; ???????????? ????????????p = mmap( NULL, xres*yres*4, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0 ); ????????????if( !p ){ ????????????????printf( "mmap failed\n" ); ????????????????return; ????????????} ???????? ????????????/* draw default color with alpha : all pass through*/ ????????????for( j = 0; j < yres; j++ ){ ????????????????for( i = 0; i < xres ; i++ ){ ????????????????????*( p + j * xres + i ) = 0x00FFFFFF; ????????????????} ????????????} ???????? ????????????/* draw color */ ????????????for( j = 0; j < yres; j++ ){ ????????????????for( i = 0; i < fb_x[win] ; i++ ){ ????????????????????*( p + j * xres + i ) = fb_color[win]; ????????????????} ????????????} ???????? ????????????munmap( p, xres*yres*4 ); ????????} ???????? ????????int main( int argc, char *argv[] ) ????????{ ????????????int i; ????????????int ret; ????????????struct fb_var_screeninfo var; ????????????int????blank; ????????????int fd[ WIN_MAX ]; ???????? ????????????/* initial */ ????????????memset( fd, -1, sizeof( fd ) ); ???????? ????????????/* open framebuffer */ ????????????for( i=0; i<WIN_MAX; i++ ){ ????????????????fd[i] = open( fb_file_path[i], O_RDWR ); ????????????????if( fd[i] < 0 ){ ????????????????????printf( "open %s failed\n", fb_file_path[i] ); ????????????????????goto end; ????????????????} ????????????} ????????????printf( "open framebuffer ok\n" ); ???????? ????????????/* set screen info */ ????????????ret = ioctl( fd[WIN2], FBIOGET_VSCREENINFO, &var ); ????????????if( ret < 0 ){ ????????????????printf( "ioctl %s FBIOGET_VSCREENINFO failed\n", fb_file_path[WIN2] ); ????????????????goto end; ????????????} ???????? ????????????var.activate = FB_ACTIVATE_FORCE; ????????????var.yres_virtual = var.yres; ???????????? ????????????for( i=0; i<WIN_MAX; i++ ){ ????????????????ret = ioctl( fd[i], FBIOPUT_VSCREENINFO, &var ); ????????????????if( ret < 0 ){ ????????????????????printf( "ioctl %s FBIOPUT_VSCREENINFO failed\n", fb_file_path[i] ); ????????????????????goto end; ????????????????} ????????????} ????????????printf( "set screeninfo ok\n" ); ???????? ????????????/* draw some color */ ????????????for( i=0; i<WIN_MAX; i++ ){ ????????????????draw_framebuffer( i, fd[i], var.xres, var.yres ); ????????????} ????????????printf( "draw color ok\n" ); ???????? ????????????/* show window */ ????????????blank = FB_BLANK_UNBLANK; ???????? ????????????for( i=0; i<WIN_MAX; i++ ){ ????????????????ret = ioctl( fd[i], FBIOBLANK, blank ); ????????????????if( ret < 0 ){ ????????????????????printf( "ioctl %s FBIOBLANK failed\n", fb_file_path[i] ); ????????????????????goto end; ????????????????} ????????????} ????????????printf( "show window ok\n" ); ???????? ????????????/* wait input */???? ????????????getchar(); ????????end: ????????????return 0; ????????}

????????
????下面是屏幕截圖，其實(shí)我對(duì) RGB 不太了解，不知到什么值應(yīng)該是什么顏色，但 只描畫了紅/綠/藍(lán) 三種顏色，而屏幕上不是這三種顏色。
????說明 alpha blending 應(yīng)該是正常工作了的。

?????????
?

END

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