4.11.3.9. NXP i.MX8MQ EVK Evaluation Board

Board comes with:

• 3GiB of LPDDR4 RAM
• 16GiB eMMC

Not including booting via serial, the device can boot from either SD or eMMC.

4.11.3.9.1. Downloading DDR PHY Firmware

As a part of DDR intialization routine NXP i.MX8MQ EVK requires and uses several binary firmware blobs that are distributed under a separate EULA and cannot be included in Barebox. In order to obtain them do the following:

wget https://www.nxp.com/lgfiles/NMG/MAD/YOCTO/firmware-imx-7.2.bin
chmod +x firmware-imx-7.2.bin
./firmware-imx-7.2.bin

Executing that file should produce a EULA acceptance dialog as well as result in the following files:

• lpddr4_pmu_train_1d_dmem.bin
• lpddr4_pmu_train_1d_imem.bin
• lpddr4_pmu_train_2d_dmem.bin
• lpddr4_pmu_train_2d_imem.bin

As a last step of this process those files need to be placed in “firmware/imx/”:

for f in lpddr4_pmu_train_1d_dmem.bin  \
         lpddr4_pmu_train_1d_imem.bin  \
         lpddr4_pmu_train_2d_dmem.bin  \
         lpddr4_pmu_train_2d_imem.bin; \
do \
         cp firmware-imx-7.2/firmware/ddr/synopsys/${f} \
            firmware/imx/${f}; \
done

4.11.3.10. DDR Configuration Code

The following two files:

• ddr_init.c
• ddrphy_train.c

were obtained by running i.MX 8M DDR Tool that can be found here:

https://community.nxp.com/docs/DOC-340179

Only minimal amount of necessary changes were made to those files. All of the “impedance matching” code is located in “ddr.h”.

4.11.3.11. Build Barebox

make imx_v8_defconfig make

4.11.3.12. Boot Configuration

The NXM i.MX8MQ EVK Evaluation Board has two switches responsible for configuring bootsource/boot mode:

• SW802 for selecting appropriate BMOD
• SW801 for selecting appropriate boot medium

In order to select internal boot set SW802 as follows:

+-----+
|     |
| O | | <--- on = high level
| | | |
| | O | <--- off = low level
|     |
| 1 2 |
+-----+

Bootsource is the internal eMMC:

+---------+
|         |
| | | O | |
| | | | | |  <---- eMMC
| O O O O |
|         |
| 1 2 3 4 |
+---------+

Bootsource is the SD2 slot:

+---------+
|         |
| O O | | |
| | | | | |  <---- SD2
| | | O O |
|         |
| 1 2 3 4 |
+---------+

Serial boot SW802 setting needed for i.MX8 DDR Tool is as follows:

+-----+
|     |
| | O | <--- on = high level
| | | |
| O | | <--- off = low level
|     |
| 1 2 |
+-----+