LVDS0 in U-Boot 2015.04 at imx6qSabreSD-based board.

[ivannikolaenko]

Hi all!

I am trying to display SplashScreen logo at LVDS display in U-Boot. My mx6sabre_common.h configs is next:

/* Framebuffer */
#define CONFIG_VIDEO
#define CONFIG_VIDEO_IPUV3
#define CONFIG_CFB_CONSOLE
#define CONFIG_VGA_AS_SINGLE_DEVICE
#define CONFIG_SYS_CONSOLE_IS_IN_ENV
#define CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
#define CONFIG_VIDEO_BMP_RLE8
#define CONFIG_SPLASH_SCREEN
#define CONFIG_SPLASH_SCREEN_ALIGN
#define CONFIG_BMP_16BPP
#define CONFIG_VIDEO_LOGO
#define CONFIG_VIDEO_BMP_LOGO
#define CONFIG_IPUV3_CLK 260000000
#define CONFIG_IMX_HDMI
#define CONFIG_IMX_VIDEO_SKIP

Now I can see crystal clear logo at the HDMI channel, but when I unplug HDMI and plug LVDS and reboot board I see my logo badly corrupted.

My LVDS display is interfaced over LVDS0 0-3 data lanes

LVDS0_TX0_N

LVDS0_TX0_P

LVDS0_TX1_N

LVDS0_TX1_P

LVDS0_TX2_N

LVDS0_TX2_P

LVDS0_TX3_N

LVDS0_TX3_P

Here are my LVDS-related code snippets:

static void enable_lvds(struct display_info_t const *dev)
{
    struct iomuxc *iomux = (struct iomuxc *)
                IOMUXC_BASE_ADDR;
    u32 reg = readl(&iomux->gpr[2]);
    reg |= IOMUXC_GPR2_DATA_WIDTH_CH0_24BIT |
           IOMUXC_GPR2_DATA_WIDTH_CH1_24BIT;
    writel(reg, &iomux->gpr[2]);
}
struct display_info_t const displays[] = {{
    .bus    = -1,
    .addr    = 0,
    .pixfmt    = IPU_PIX_FMT_RGB666,
    .detect    = NULL,
    .enable    = enable_lvds,
    .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_NONINTERLACED
} }, {
    .bus    = -1,
    .addr    = 0,
    .pixfmt    = IPU_PIX_FMT_RGB24,
    .detect    = detect_hdmi,
    .enable    = do_enable_hdmi,
    .mode    = {
        .name           = "HDMI",
        .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_NONINTERLACED
} }};

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_24BIT
         | IOMUXC_GPR2_BIT_MAPPING_CH0_SPWG
         | IOMUXC_GPR2_DATA_WIDTH_CH0_24BIT
         | IOMUXC_GPR2_LVDS_CH0_MODE_ENABLED_DI0
         | IOMUXC_GPR2_LVDS_CH1_MODE_DISABLED;
    writel(reg, &iomux->gpr[2]);
    reg = readl(&iomux->gpr[3]);
    reg = (reg & ~(IOMUXC_GPR3_LVDS0_MUX_CTL_MASK
            | IOMUXC_GPR3_HDMI_MUX_CTL_MASK))
        | (IOMUXC_GPR3_MUX_SRC_IPU1_DI0
           << IOMUXC_GPR3_LVDS0_MUX_CTL_OFFSET);
    writel(reg, &iomux->gpr[3]);
}

And another question: Is it possible to simultaneously display HDMI and LVDS0 at U-Boot?

I have not found answers to their questions on the forum.

Hope for your help!

Regards,

Ivan.

[alejandrolozan1]

Hi,

Just to clarify, you are trying that the logo shows up in either HDMI monitor or LVDS display depending on which one is detected?

Or you just want to display the logo in both screens? This is of course possible in HW but I have to skim through the u-boot code to try to add this feature.

Please provide more details about what you have tried in the code, I would be glad to help.

Best Regards,

Alejandro

[ivannikolaenko]

Hi, Alejandro.

Thank you for your responce.

I want to display my logo in both screens at the same time. Problem is that I can't get LVDS0 working. I started to change mx6sabresd.c source file. I realized that in order for the screen displayed something I need set DATA_WIDTH to 24BIT. There are two possible ways: SPWG and JEIDA.

For SPWG:

diff --git a/board/freescale/mx6sabresd/mx6sabresd.c b/board/freescale/mx6sabresd/mx6sabresd.c
index 4198f61..b9804ef 100644
--- a/board/freescale/mx6sabresd/mx6sabresd.c
+++ b/board/freescale/mx6sabresd/mx6sabresd.c
 static iomux_v3_cfg_t const usdhc4_pads[] = {
@@ -438,9 +438,10 @@ static void enable_lvds(struct display_info_t const *dev)
        struct iomuxc *iomux = (struct iomuxc *)
                                IOMUXC_BASE_ADDR;
        u32 reg = readl(&iomux->gpr[2]);
-       reg |= IOMUXC_GPR2_DATA_WIDTH_CH0_18BIT |
-              IOMUXC_GPR2_DATA_WIDTH_CH1_18BIT;
+       reg |= IOMUXC_GPR2_DATA_WIDTH_CH0_24BIT |
+              IOMUXC_GPR2_DATA_WIDTH_CH1_24BIT;
        writel(reg, &iomux->gpr[2]);
+       //gpio_direction_output(DISP0_PWR_EN, 1);
 }
 struct display_info_t const displays[] = {{
@@ -546,18 +547,18 @@ static void setup_display(void)
             | 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_DATA_WIDTH_CH1_24BIT
             | IOMUXC_GPR2_BIT_MAPPING_CH0_SPWG
-            | IOMUXC_GPR2_DATA_WIDTH_CH0_18BIT
-            | IOMUXC_GPR2_LVDS_CH0_MODE_DISABLED
-            | IOMUXC_GPR2_LVDS_CH1_MODE_ENABLED_DI0;
+            | IOMUXC_GPR2_DATA_WIDTH_CH0_24BIT
+            | IOMUXC_GPR2_LVDS_CH0_MODE_ENABLED_DI0
+            | IOMUXC_GPR2_LVDS_CH1_MODE_DISABLED;
        writel(reg, &iomux->gpr[2]);
        reg = readl(&iomux->gpr[3]);
-       reg = (reg & ~(IOMUXC_GPR3_LVDS1_MUX_CTL_MASK
+       reg = (reg & ~(IOMUXC_GPR3_LVDS0_MUX_CTL_MASK
                        | IOMUXC_GPR3_HDMI_MUX_CTL_MASK))
            | (IOMUXC_GPR3_MUX_SRC_IPU1_DI0
-              << IOMUXC_GPR3_LVDS1_MUX_CTL_OFFSET);
+              << IOMUXC_GPR3_LVDS0_MUX_CTL_OFFSET);
        writel(reg, &iomux->gpr[3]);
 }
 #endif /* CONFIG_VIDEO_IPUV3 */

I got this:

For JEIDA:

diff --git a/board/freescale/mx6sabresd/mx6sabresd.c b/board/freescale/mx6sabresd/mx6sabresd.c
index 4198f61..ea618aa 100644
--- a/board/freescale/mx6sabresd/mx6sabresd.c
+++ b/board/freescale/mx6sabresd/mx6sabresd.c 
 static iomux_v3_cfg_t const usdhc4_pads[] = {
@@ -438,9 +438,10 @@ static void enable_lvds(struct display_info_t const *dev)
        struct iomuxc *iomux = (struct iomuxc *)
                                IOMUXC_BASE_ADDR;
        u32 reg = readl(&iomux->gpr[2]);
-       reg |= IOMUXC_GPR2_DATA_WIDTH_CH0_18BIT |
-              IOMUXC_GPR2_DATA_WIDTH_CH1_18BIT;
+       reg |= IOMUXC_GPR2_DATA_WIDTH_CH0_24BIT |
+              IOMUXC_GPR2_DATA_WIDTH_CH1_24BIT;
        writel(reg, &iomux->gpr[2]);
+       //gpio_direction_output(DISP0_PWR_EN, 1);
 }
 struct display_info_t const displays[] = {{
@@ -546,18 +547,18 @@ static void setup_display(void)
             | 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_CH0_MODE_DISABLED
-            | IOMUXC_GPR2_LVDS_CH1_MODE_ENABLED_DI0;
+            | IOMUXC_GPR2_DATA_WIDTH_CH1_24BIT
+            | IOMUXC_GPR2_BIT_MAPPING_CH0_JEIDA
+            | IOMUXC_GPR2_DATA_WIDTH_CH0_24BIT
+            | IOMUXC_GPR2_LVDS_CH0_MODE_ENABLED_DI0
+            | IOMUXC_GPR2_LVDS_CH1_MODE_DISABLED;
        writel(reg, &iomux->gpr[2]);
        reg = readl(&iomux->gpr[3]);
-       reg = (reg & ~(IOMUXC_GPR3_LVDS1_MUX_CTL_MASK
+       reg = (reg & ~(IOMUXC_GPR3_LVDS0_MUX_CTL_MASK
                        | IOMUXC_GPR3_HDMI_MUX_CTL_MASK))
            | (IOMUXC_GPR3_MUX_SRC_IPU1_DI0
-              << IOMUXC_GPR3_LVDS1_MUX_CTL_OFFSET);
+              << IOMUXC_GPR3_LVDS0_MUX_CTL_OFFSET);
        writel(reg, &iomux->gpr[3]);
 }
 #endif /* CONFIG_VIDEO_IPUV3 */

I got this:

Original image at the HDMI (from U-Boot):

That is all that I tried to change.

Please help me to understand what is the problem.

[alejandrolozan1 · Accepted solution]

Hi,

Have you checked that the frequency for the lvds panel is the correct one?

/Alejandro

[ivannikolaenko]

Hi, Alejandro!

We started to check the frequency as you advised and found that we have a LVDS_TX3 pair instead of a LVDS_CLK pair :smileyconfused:.

We rerouted this wires and LVDS started work perfectly!

Thank you!