LPDDR Memory - Qualcomm Dragonwing Documentation

The Qualcomm Dragonwing IQ-9075 features an advanced memory subsystem designed for high-performance computing applications.

Specifications

Specification	Details
Memory Type	LPDDR5X / LPDDR5 SDRAM
Configuration	Six-channel non-PoP
Maximum Density	36 GB
Clock Speed	Up to 3200 MHz
Data Width	6 × 16-bit (96-bit total)
Standards	JEDEC LPDDR5X/LPDDR5 compliant

Architecture

The IQ-9075 memory controller supports high-bandwidth, low-latency operations across six independent 16-bit channels with dynamic frequency scaling for power optimization. The IQ-9075M module has three 12 GB LPDDR5 SDRAM ICs:

Supported DRAM Components

All DRAM components must be selected from the Qualcomm Preferred Vendor List (PVL).

Access the PVL database

Navigate to the Qualcomm PVL and sign in with your Qualcomm account.

Download the PVL file

Download the QRD Hardware - Preferred Vendor List (PVL) Excel file.

Filter for IQ-9075 memory

Filter by Type: Memory and Chipset: IQ-9075.

Initialization

Setup and Configuration

Prerequisites

IQ-9075 development board with PVL-compliant LPDDR5X or LPDDR5 DRAM
Canonical Ubuntu software package
XBL bootloader with DSF (DDR System Firmware)
UART debug cable and SSH access

Initial Setup

Verify DRAM component

Confirm your DRAM part number is listed in the Qualcomm PVL for IQ-9075.

Flash the software package

fastboot flash xbl xbl.elf
fastboot flashall

Boot and verify detection

Connect UART console (115200 baud, 8N1) and watch for initialization messages:

sbl1_ddr_init, Start
LP5 DDR detected
Manufacturer ID = XXXX, Device Type = XXXX
Rank 0 size = XXXX MB, Rank 1 size = XXXX MB
Max enabled DDR Freq = 3200 MHz

Frequency Scaling

# Check current DRAM frequency
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/cur_freq

# List available frequencies
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/available_frequencies

# Set specific frequency (requires root)
echo <frequency> > /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/userspace/set_freq

Memory Bandwidth Monitoring

cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/cur_freq
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/load
cat /proc/meminfo

Debugging

Boot Log Analysis

Log Entry	Description	Action if Missing
`sbl1_ddr_init, Start`	DRAM initialization begins	Check XBL image integrity
`<LP5> DDR detected`	DRAM type detected	Verify DRAM component compatibility
`Manufacturer ID = <XXXX>`	DRAM identification	Cross-reference with PVL
`Rank 0 size = <XXXX> MB`	Density detection	Check DRAM module installation
`Max enabled DDR Freq = <XXXX> MHz`	Maximum frequency	Verify frequency configuration
`DDR Frequency, <XXXX> MHz`	Operating frequency set	Verify frequency matches spec

# Search boot log for DRAM entries
grep -i "ddr\|dram\|memory" boot.log

# Check for errors
grep -i "error\|fail\|panic" boot.log

Diagnostic Commands

# Check DRAM detection in boot logs
dmesg | grep -i ddr
dmesg | grep -i memory

# Display memory information
cat /proc/meminfo

# Verify operating frequency
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/cur_freq

# Check kernel memory map
cat /proc/iomem | grep -i memory

# Check for ECC errors
dmesg | grep -i ecc
cat /sys/devices/system/edac/mc/mc*/ce_count
cat /sys/devices/system/edac/mc/mc*/ue_count

Troubleshooting

DRAM Not Detected at Boot

Symptoms: No DRAM detection in UART logs; boot hangs at XBL stage.Steps:

Verify DRAM modules are properly seated with no physical damage
Measure VDD and VDDQ voltages — ensure they meet JEDEC specifications
Check for voltage droops during boot
Verify clock signal presence and data line connectivity

Resolution: Reseat DRAM modules, fix power supply issues, or contact Qualcomm support.

Wrong DRAM Type Detected

Symptoms: Detected type doesn’t match installed component; incorrect manufacturer ID; wrong memory size.Steps:

Check log for Manufacturer ID = <XXXX>, Device Type = <XXXX>
Verify DRAM part number against PVL
Inspect physical markings on DRAM chips

Resolution: Replace with PVL-approved component; verify procurement source for authenticity.

DRAM Initialization Fails

Symptoms: Boot hangs after DRAM detection; training/calibration failures; intermittent boot failures.Steps:

Check temperature (must be within spec) and voltage stability
Measure signal quality on all channels; verify impedance matching
Try booting at a lower frequency — success indicates signal integrity issue

Resolution: Improve signal integrity (routing, termination); adjust timing parameters (contact Qualcomm).

Memory Corruption During Runtime

Symptoms: Random application crashes, kernel panics, data corruption.Steps:

# Monitor for errors
dmesg -w | grep -i "corruption\|error"

# Check DRAM temperature
cat /sys/class/thermal/thermal_zone*/temp

Resolution: Improve thermal management, fix power supply issues, replace failing DRAM modules.

Performance Below Specification

Symptoms: Memory bandwidth lower than expected; high latency; system performance degradation.Steps:

# Check current frequency (should be up to 3200 MHz)
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/cur_freq

# Check governor and throttling
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/governor
cat /sys/class/thermal/thermal_zone*/temp

Resolution: Set performance governor, improve cooling, verify DRAM component supports full speed.

Insufficient Memory Available

Symptoms: Less memory than installed; out-of-memory errors; allocation failures.Steps:

# Check total memory (should show up to 36 GB)
cat /proc/meminfo | grep MemTotal

# Check reserved regions
cat /proc/iomem | grep -i reserved

# Identify memory consumers
ps aux --sort=-%mem | head -20

Resolution: Verify all DRAM modules are detected; review reserved memory configuration; fix memory leaks.

Performance Optimization

Frequency Governor

# Maximum performance
echo performance > /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/governor

# Power-optimized
echo ondemand > /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/governor

# Manual frequency
echo userspace > /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/governor
echo 3200000000 > /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/userspace/set_freq

Cache and Access Patterns

# Check cache configuration
cat /sys/devices/system/cpu/cpu*/cache/index*/size
cat /sys/devices/system/cpu/cpu*/cache/index*/type

Best practices:

Prefer sequential over random memory access
Align data structures to cache line boundaries
Pre-allocate memory when possible to minimize allocation overhead
Use huge pages for large allocations

Monitoring

# Real-time memory usage
watch -n 1 free -h

# Bandwidth load
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/load

# Cache miss profiling
perf stat -e cache-misses,cache-references <application>

Resources

Resource	URL
JEDEC LPDDR Standards	https://www.jedec.org/category/technology-focus-area/mobile-memory-lpddr-wide-io-memory-mcp
Qualcomm PVL	https://www.qualcomm.com/preferred-vendor-list
Qualcomm Software Center	https://softwarecenter.qualcomm.com/#/

​Specifications

​Architecture

​Supported DRAM Components

​Initialization

​Setup and Configuration

​Prerequisites

​Initial Setup

​Frequency Scaling

​Memory Bandwidth Monitoring

​Debugging

​Boot Log Analysis

​Diagnostic Commands

​Troubleshooting

​Performance Optimization

​Frequency Governor

​Cache and Access Patterns

​Monitoring

​Resources