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

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Specifications

SpecificationDetails
Memory TypeLPDDR5X / LPDDR5 SDRAM
ConfigurationSix-channel non-PoP
Maximum Density36 GB
Clock SpeedUp to 3200 MHz
Data Width6 × 16-bit (96-bit total)
StandardsJEDEC LPDDR5X/LPDDR5 compliant

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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:

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Supported DRAM Components

All DRAM components must be selected from the Qualcomm Preferred Vendor List (PVL).
1

Access the PVL database

Navigate to the Qualcomm PVL and sign in with your Qualcomm account.
2

Download the PVL file

Download the QRD Hardware - Preferred Vendor List (PVL) Excel file.
3

Filter for IQ-9075 memory

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

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Initialization

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Setup and Configuration

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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

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Initial Setup

1

Verify DRAM component

Confirm your DRAM part number is listed in the Qualcomm PVL for IQ-9075.
2

Flash the software package

fastboot flash xbl xbl.elf
fastboot flashall
3

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

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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

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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

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Debugging

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Boot Log Analysis

Log EntryDescriptionAction if Missing
sbl1_ddr_init, StartDRAM initialization beginsCheck XBL image integrity
<LP5> DDR detectedDRAM type detectedVerify DRAM component compatibility
Manufacturer ID = <XXXX>DRAM identificationCross-reference with PVL
Rank 0 size = <XXXX> MBDensity detectionCheck DRAM module installation
Max enabled DDR Freq = <XXXX> MHzMaximum frequencyVerify frequency configuration
DDR Frequency, <XXXX> MHzOperating frequency setVerify 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

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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

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Troubleshooting

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.
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.
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).
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.
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.
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.

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Performance Optimization

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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

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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

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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>

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Resources

ResourceURL
JEDEC LPDDR Standardshttps://www.jedec.org/category/technology-focus-area/mobile-memory-lpddr-wide-io-memory-mcp
Qualcomm PVLhttps://www.qualcomm.com/preferred-vendor-list
Qualcomm Software Centerhttps://softwarecenter.qualcomm.com/#/