imx6-uboot添加lvds1显示

问题引出：客户使用lvds1显示uboot不出图像

问题解决：

1. 查看uboot显示部分的源码

static void setup_display(void)
{
	struct mxc_ccm_reg *mxc_ccm = (struct mxc_ccm_reg *)CCM_BASE_ADDR;
	struct iomuxc *iomux = (struct iomuxc *)IOMUXC_BASE_ADDR;
	int reg;

	/* Setup HSYNC, VSYNC, DISP_CLK for debugging purposes */
	imx_iomux_v3_setup_multiple_pads(di0_pads, ARRAY_SIZE(di0_pads));

	enable_ipu_clock();
	imx_setup_hdmi();

	/* Turn on LDB0, LDB1, IPU,IPU DI0 clocks */
	reg = readl(&mxc_ccm->CCGR3);
	reg |=  MXC_CCM_CCGR3_LDB_DI0_MASK | MXC_CCM_CCGR3_LDB_DI1_MASK;
	writel(reg, &mxc_ccm->CCGR3);

	/* set LDB0, LDB1 clk select to 011/011 */
	reg = readl(&mxc_ccm->cs2cdr);
	reg &= ~(MXC_CCM_CS2CDR_LDB_DI0_CLK_SEL_MASK
		 | MXC_CCM_CS2CDR_LDB_DI1_CLK_SEL_MASK);
	reg |= (3 << MXC_CCM_CS2CDR_LDB_DI0_CLK_SEL_OFFSET)
	      | (3 << MXC_CCM_CS2CDR_LDB_DI1_CLK_SEL_OFFSET);
	writel(reg, &mxc_ccm->cs2cdr);

	reg = readl(&mxc_ccm->cscmr2);
	reg |= MXC_CCM_CSCMR2_LDB_DI0_IPU_DIV | MXC_CCM_CSCMR2_LDB_DI1_IPU_DIV;
	writel(reg, &mxc_ccm->cscmr2);

	reg = readl(&mxc_ccm->chsccdr);
	reg |= (CHSCCDR_CLK_SEL_LDB_DI0
		<< MXC_CCM_CHSCCDR_IPU1_DI0_CLK_SEL_OFFSET);
	reg |= (CHSCCDR_CLK_SEL_LDB_DI0
		<< MXC_CCM_CHSCCDR_IPU1_DI1_CLK_SEL_OFFSET);
	writel(reg, &mxc_ccm->chsccdr);

	reg = IOMUXC_GPR2_BGREF_RRMODE_EXTERNAL_RES
	     | IOMUXC_GPR2_DI1_VS_POLARITY_ACTIVE_LOW
	     | IOMUXC_GPR2_DI0_VS_POLARITY_ACTIVE_LOW
	     | IOMUXC_GPR2_BIT_MAPPING_CH1_SPWG
	     | IOMUXC_GPR2_DATA_WIDTH_CH1_18BIT
	     | IOMUXC_GPR2_BIT_MAPPING_CH0_SPWG
	     | IOMUXC_GPR2_DATA_WIDTH_CH0_18BIT
	     | IOMUXC_GPR2_LVDS_CH1_MODE_DISABLED
	     | IOMUXC_GPR2_LVDS_CH0_MODE_ENABLED_DI0;
	writel(reg, &iomux->gpr[2]);

	reg = readl(&iomux->gpr[3]);
	reg = (reg & ~(IOMUXC_GPR3_LVDS1_MUX_CTL_MASK
			| IOMUXC_GPR3_HDMI_MUX_CTL_MASK))
	    | (IOMUXC_GPR3_MUX_SRC_IPU1_DI0
	       << IOMUXC_GPR3_LVDS1_MUX_CTL_OFFSET);
	writel(reg, &iomux->gpr[3]);
}

梳理了一下寄存器的值

diff --git a/board/freescale/mx6sabresd/mx6sabresd.c b/board/freescale/mx6sabresd/mx6sabresd.c
index cf84090..15252cb 100644
--- a/board/freescale/mx6sabresd/mx6sabresd.c
+++ b/board/freescale/mx6sabresd/mx6sabresd.c
@@ -1013,6 +1013,11 @@ static void setup_display(void)
 	reg |=  MXC_CCM_CCGR3_LDB_DI0_MASK | MXC_CCM_CCGR3_LDB_DI1_MASK;
 	writel(reg, &mxc_ccm->CCGR3);
 
+	/* Turn on ipu1_ipu_di0_clk and ipu1_ipu_di1_clk */
+	reg = readl(&mxc_ccm->CCGR3);
+	reg |=  MXC_CCM_CCGR3_IPU1_IPU_DI0_MASK | MXC_CCM_CCGR3_IPU1_IPU_DI1_MASK;
+	writel(reg, &mxc_ccm->CCGR3);
+
 	/* set LDB0, LDB1 clk select to 011/011 */
 	reg = readl(&mxc_ccm->cs2cdr);
 	reg &= ~(MXC_CCM_CS2CDR_LDB_DI0_CLK_SEL_MASK
@@ -1039,10 +1044,9 @@ static void setup_display(void)
 	     | IOMUXC_GPR2_DATA_WIDTH_CH1_18BIT
 	     | IOMUXC_GPR2_BIT_MAPPING_CH0_SPWG
 	     | IOMUXC_GPR2_DATA_WIDTH_CH0_18BIT
-	     | IOMUXC_GPR2_LVDS_CH1_MODE_DISABLED
+	     | IOMUXC_GPR2_LVDS_CH1_MODE_ENABLED_DI0
 	     | IOMUXC_GPR2_LVDS_CH0_MODE_ENABLED_DI0;
 	writel(reg, &iomux->gpr[2]);
-
 	reg = readl(&iomux->gpr[3]);
 	reg = (reg & ~(IOMUXC_GPR3_LVDS1_MUX_CTL_MASK
 			| IOMUXC_GPR3_HDMI_MUX_CTL_MASK))
diff --git a/common/cmd_scr_menu.c b/common/cmd_scr_menu.c
index 9c31aec..a96d1b3 100644
--- a/common/cmd_scr_menu.c
+++ b/common/cmd_scr_menu.c
@@ -46,7 +46,7 @@ int mxcfb0(void)
                         break;
                 case '4':
                         setenv("panel","LDB-WXGA");
-                        setenv("mxcfb0","video=mxcfb0:dev=ldb,1280x800M@60,if=RGB24,bpp=16");
+                        setenv("mxcfb0","video=mxcfb0:dev=ldb,LDB-WXGA,if=RGB24,bpp=16");
                         break;
                 case '5':
                         //setenv("panel","HDMI");

然后uboot 选择屏幕参数为mxcfb0","video=mxcfb0:dev=ldb,LDB-WXGA,if=RGB24,bpp=16
LDB-WXGA为具体的屏幕参数结构体