uboot-lvds-panel-configuration

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uboot lvds panel configuration

Environment

U-BOOT version: 2014

Source Reference:

Git: http://git.freescale.com/git/cgit.cgi/imx/uboot-imx.git/
Branch: imx_v2014.04_3.10.53_1.1.0_ga File: ~/board/freescale/mx6sabresd/mx6sabresd.c

reference example

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static struct display_info_t const displays[] {
{
	.bus	= -1,
	.addr	= 0,
	.pixfmt = IPU_PIX_FMT_RGB666, 	// IPU_PIX_FMT_RGB24
	.detect = NULL,
	.enable = NULL,
	.mode = {
		.name				= "Hannstar-XGA",
		.refresh			= 60,
		.xres				= 1024,
		.yres				= 768,
		.pixclock			= 15385,
		.left_margin		= 220,
		.right_margin		= 40,
		.upper_margin		= 21,
		.lower_margin		= 7,
		.hsync_len		= 60,
		.vsync_len		= 10,
		.sync				= FB_SYNC_EXT,
		.vmode				= FB_VMODE_MONINTERLAED,
	}
},

  • pixfmt: 18bit or 24bit

    • IPU_PIX_FMT_RGB666 

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      	static void setup_display(void)
      		{
      			...
      			reg = IOMUXC_GPR2_BGREF_PRMODE_EXTERNAL_RES
      			...
      				| IOMUXC_GPR2_DATA_WIDTH_CH1_18BIT
      			...
      				| IOMUXC_GPR2_DATA_WIDTH_CH0_18BIT
      		}
      	```	
      - `IPU_PIX_FMT_RGB24`

      static void setup_display(void)

      {
    ...
    reg = IOMUXC_GPR2_BGREF_PRMODE_EXTERNAL_RES
    ...
        | IOMUXC_GPR2_DATA_WIDTH_CH1_24BIT
    ...
        | IOMUXC_GPR2_DATA_WIDTH_CH0_24BIT
}

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      - name: panel name checked in boot-env setting `panel`
      - refresh: refresh rate, set to typical
      - xres:	x resolution / active width / H-display area
      - yres:	y resolution / active height / V-display area 
      - pixclock: pixel clock
      	- calculate formula: `pixclock=(10^12)/clk_freq` (clk_freq: DCLK freq)
      	- pixclock = `10^12 / (1024+220+40+60) * (768+21+7+10) * 60` = `15385 ps` (ps: pico-sencond, 10^(-12) second
      - Horizontal
      	- left_margin: left margin / HS back porch (HBP)
      	- right_margin: right margin / HS front porch (HFP)
      	- hsync_len: horizontal sync length / HS pulse width (HPW)
      	- Horizontal blanking time: HBP + HFP
      - Vertical
      	- upper_margin: upper margin / VS back porch (VBP)
      	- lower_margin: lower margin / VS front porch (VFP)
      	- vsync_len: vertical sync length / VS pulse width (VPW)
      	- Vertical blanking time: VBP + VFP
      - sync: FB_SYNC_EXT, external sync
      ~/drivers/video/videomodes.h
      - vmode: this is a progressive video mode, so set vmode to FB_VMODE_NONINTERLACED.
      ~/drivers/video/videomodes.h
      ## HDMI Full HD 1920x1080

{ .bus = -1, .addr = 0, .pixfmt = IPU_PIX_FMT_RGB24, .detect = NULL, .enable = do_enable_hdmi, .mode = { .name = “HDMI”, .refresh = 60, .xres = 640, .yres = 480, .pixclock = 39721, .left_margin = 48, .right_margin = 16, .upper_margin = 33, .lower_margin = 10, .hsync_len = 96, .vsync_len = 2, .sync = 0, .vmode = FB_VMODE_NONINTERLACED } } ```