OK, I have created my own SEMC init function (from the code in glcd_tft.h) and that seems to work. This would seem to indicate that either the DCD data is not correct or not getting applied in the uTaskerBoot code...
Here is the SEMC init code I am using:
void fnInitSEMC(void) {
#if (defined MIMXRT1050 || defined iMX_RT1052_EMB_ART || defined iMX_RT1062_EMB_ART || defined MIMXRT1060 || defined MIMXRT1064) // {8}
#if (!defined SDRAM_CONFIGURED_BY_DCD)
// Configure SEMC pins and SDRAM (IS42S16160J-6BLI)
//
_CONFIG_PERIPHERAL(GPIO_EMC_00, SEMC_DATA00,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA00 on GPIO4-00 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_01, SEMC_DATA01,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA01 on GPIO4-01 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_02, SEMC_DATA02,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA02 on GPIO4-02 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_03, SEMC_DATA03,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA03 on GPIO4-03 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_04, SEMC_DATA04,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA04 on GPIO4-04 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_05, SEMC_DATA05,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA05 on GPIO4-05 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_06, SEMC_DATA06,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA06 on GPIO4-06 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_07, SEMC_DATA07,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA07 on GPIO4-07 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_30, SEMC_DATA08,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA08 on GPIO4-30 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_31, SEMC_DATA09,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA09 on GPIO4-31 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_32, SEMC_DATA10,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA10 on GPIO3-18 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_33, SEMC_DATA11,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA11 on GPIO3-19 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_34, SEMC_DATA12,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA12 on GPIO3-20 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_35, SEMC_DATA13,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA13 on GPIO3-21 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_36, SEMC_DATA14,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA14 on GPIO3-22 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_37, SEMC_DATA15,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DATA15 on GPIO3-23 - alt function 0 (direction input/output)
_CONFIG_PERIPHERAL(GPIO_EMC_09, SEMC_ADDR00,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR00 on GPIO4-09 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_10, SEMC_ADDR01,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR01 on GPIO4-10 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_11, SEMC_ADDR02,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR02 on GPIO4-11 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_12, SEMC_ADDR03,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR03 on GPIO4-12 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_13, SEMC_ADDR04,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR04 on GPIO4-13 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_14, SEMC_ADDR05,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR05 on GPIO4-14 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_15, SEMC_ADDR06,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR06 on GPIO4-15 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_16, SEMC_ADDR07,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR07 on GPIO4-16 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_17, SEMC_ADDR08,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR08 on GPIO4-17 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_18, SEMC_ADDR09,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR09 on GPIO4-18 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_23, SEMC_ADDR10,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR10 on GPIO4-23 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_19, SEMC_ADDR11,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR11 on GPIO4-19 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_20, SEMC_ADDR12,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_ADDR12 on GPIO4-20 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_21, SEMC_BA0,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_BA0 on GPIO4-21 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_22, SEMC_BA1,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_BA1 on GPIO4-22 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_24, SEMC_CAS,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_CAS on GPIO4-24 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_25, SEMC_RAS,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_RAS on GPIO4-25 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_26, SEMC_CLK,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_CLK on GPIO4-26 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_27, SEMC_CKE,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_CKE on GPIO4-27 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_28, SEMC_WE,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_WE on GPIO4-28 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_29, SEMC_CS0,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_CS0 on GPIO4-29 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_08, SEMC_DM00,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DM00 on GPIO4-08 - alt function 0 (direction output)
_CONFIG_PERIPHERAL(GPIO_EMC_38, SEMC_DM01,
(IOMUXC_SW_PAD_CTL_PAD_HYS | IOMUXC_SW_PAD_CTL_PAD_PKE | IOMUXC_SW_PAD_CTL_PAD_SPEED_MAX | IOMUXC_SW_PAD_CTL_PAD_DSE_7 | IOMUXC_SW_PAD_CTL_PAD_SRE)); // select SEMC_DM01 on GPIO3-24 - alt function 0 (direction output)
POWER_UP_ATOMIC(1, SEMC_EXSC_CLOCK);
POWER_UP_ATOMIC(3, SEMC_CLOCKS);
#if defined iMX_RT1062
#if defined APPLICATION_REQUIRES_GPIO_EMC_39
SEMC_MCR = 0; // dummy read strobe loop backed internally - maximum 60MHz operation
#else
SEMC_MCR = (SEMC_MCR_BTO_DEFAULT | SEMC_MCR_DQSMD); // DQS (read strobe) mode (maximum speed possible)
#endif
#else
#if defined APPLICATION_REQUIRES_GPIO_EMC_39
SEMC_MCR = 0; // dummy read strobe loop backed internally - maximum 60MHz operation
#else
SEMC_MCR = (SEMC_MCR_DQSMD); // DQS (read strobe) mode (maximum speed possible)
#endif
#endif
SEMC_BR0 = (SDRAM_ADDR | SEMC_BR_MS_32MB | SEMC_BR_VLD);
SEMC_IOCR = (SEMC_IOCR_MUX_RDY_NAND_RDY_WAIT | SEMC_IOCR_MUX_CSX3_DBI_CSX
| SEMC_IOCR_MUX_CSX2_NAND_CE | SEMC_IOCR_MUX_CSX1_PSRAM_CE
| SEMC_IOCR_MUX_CSX0_NOR_CE | SEMC_IOCR_MUX_A8_SDRAM_A8);
SEMC_SDRAMCR0 = 0x00000f31;
SEMC_SDRAMCR1 = 0x00652922;
SEMC_SDRAMCR2 = 0x00010920;
SEMC_SDRAMCR3 = 0x50210a08;
SEMC_DBICR0 = 0x00000021;
SEMC_DBICR1 = 0x00888888;
SEMC_IPCR1 = 0x00000002;
SEMC_IPCR2 = 0x00000000;
SEMC_IPCR0 = 0x80000000;
SEMC_IPCMD = (SEMC_IPCMD_KEY | SEMC_IPCMD_SDRAM_PRECHARGE_ALL);
_WAIT_REGISTER_FALSE(SEMC_INTR, SEMC_INTR_IPCMDDONE);
SEMC_IPCR0 = 0x80000000;
SEMC_IPCMD = (SEMC_IPCMD_KEY | SEMC_IPCMD_SDRAM_AUTO_REFRESH);
_WAIT_REGISTER_FALSE(SEMC_INTR, SEMC_INTR_IPCMDDONE);
SEMC_IPCR0 = 0x80000000;
SEMC_IPCMD = (SEMC_IPCMD_KEY | SEMC_IPCMD_SDRAM_AUTO_REFRESH);
_WAIT_REGISTER_FALSE(SEMC_INTR, SEMC_INTR_IPCMDDONE);
SEMC_IPTXDAT = 0x00000033;
SEMC_IPCR0 = 0x80000000;
SEMC_IPCMD = (SEMC_IPCMD_KEY | SEMC_IPCMD_SDRAM_MODESET);
_WAIT_REGISTER_FALSE(SEMC_INTR, SEMC_INTR_IPCMDDONE);
SEMC_SDRAMCR3 = (0x50210a08 | SEMC_SDRAMCR3_REN);
#endif
#endif
}