Hello,
We are experiencing issues during startup during training of the LPDDR4 on some of our IMX8QXP-based products.
The products reboot a few times during startup (found by measuring the reset pin), before being able to continue to the SCFW/UBoot.
The problem also manifests itself when using the MFG/UUU tool.
Multiple reboots/attempts are needed to get the UUU to go past an initial LIBUSB IO error at 18%.
DDR stress tool:
- All the products with boot issues also show to have training errors.
- Some of the faulty products only show to have training errors on some boot attempts. While others always show a training error on every boot.
- Once the DDR stress test tool gets past the initial training/startup, running the stress test does not show errors.
- The training errors show up on DDR stress test tool version ER14 and ER15.
- The training errors show up with the default SCFW binary in the stress test tool (mx8qxb0_scfw_download.bin), as well as the SCFW binary that we have compiled ourselves.
Some information about our implementation:
- MIMX8QX6AVLFZAC (c0 revision)
- SCUFW 1.15.0
- LPDDR4: Nanya (4GB) NT6AN1024F32AV-J2
- DDR config used: Copy of reference MX8QXP_C0_B0_LPDDR4_RPA_1.2GHz_v16 (MEK/Micron MT53B768M32D4) + density changed from 6Gb to 8Gb.
- Boot medium: eMMC
- We have chosen to set the fuse WDOG_ENABLE with WDOG_TIMEOUT_SELECT to 2 seconds in order to enable the SCU ROM WDOG. Perhaps this might be related.
- Linux BSP based on NXP release version 5.15.32-2.0.0
We are concerned that these issues may manifest itself over time during the life-time of the product, and eventually making the product not boot at all.
We are unsure if the issue is related to:
- hardware issues
- component tolerances
- the DDR config not covering all possible boards.
At this point we have a few questions:
- Which register settings in the excel sheet RPA could we try to change in order to make the training at boot time more reliable?
- Are there any steps we could do on the hardware in order to verify its correctness?
Please see the attachments for startup-logs of the DDR stress test tool.
Test have been performed on four products:
- DUT1: known boot issues. Stress test tool does not shows training errors on every boot.
- DUT2: known boot issues. Stress test tool shows training errors on every boot.
- DUT3: no known boot issues. No training errors in stress test tool.
- DUT4: no known boot issues. No training errors in stress test tool.
