3.2.2.6. K3 DDR
3.2.2.6.1. Introduction
The K3 DDR driver provides management and monitoring capabilities for DDR memory subsystems on Texas Instruments K3 SoCs.
The following is a list of supported K3 DDR driver features by device family:
Device Family |
Temperature Monitoring |
|---|---|
J7200 |
Yes |
AM62x LP SK/ AM62Ax / AM62Px |
Yes |
3.2.2.6.2. Building and Enabling the Driver
Kernel Configuration
The following kernel configuration enables the K3 DDR driver:
CONFIG_K3_DDR_TEMP=y
CONFIG_HWMON=y
3.2.2.6.3. Using the DDR Temperature Monitoring
By default, the DDR subsystem keeps temperature polling turned off. For allowing the kernel driver to monitor temperature, the user must enable polling during DDR configuration and initialization at boot time.
See DDR Temperature Monitoring in U-Boot documentation.
The K3 DDR driver creates a hwmon device that provides temperature status
information through sysfs. The driver registers as k3_ddr in the hwmon
subsystem for temperature monitoring functionality.
The driver reports temperature status according to LPDDR4 specification:
Value |
Temperature Status |
|---|---|
0 |
Low temperature |
1 |
4x refresh interval |
2 |
2x refresh interval |
3 |
1x refresh interval (nominal) |
4 |
0.5x refresh interval |
5 |
0.25x refresh interval |
6 |
0.25x refresh interval with derating |
7 |
High temperature |
The hwmon device should now show up in the filesystem.
root@evm:~# ls -l /sys/class/hwmon/
hwmon0
Check the current DDR temperature status:
root@evm:~# cat /sys/class/hwmon/hwmon0/device/k3_ddr_temp_status
1x refresh interval