> ## Documentation Index
> Fetch the complete documentation index at: https://dragonwingdocs.qualcomm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# LPDDR Memory

The Qualcomm Dragonwing IQ-8275 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-8275 memory controller supports high-bandwidth, low-latency operations across six independent 16-bit channels with dynamic frequency scaling for power optimization.

<img src="https://mintcdn.com/qualcomm-prod/Bh7DlgudKfjY_3Wf/Linux/images/peripheral-interfaces/memory_channel_arch.png?fit=max&auto=format&n=Bh7DlgudKfjY_3Wf&q=85&s=49f03ea0f7e8a49ee552db20a5506a30" width="1193" height="741" data-path="Linux/images/peripheral-interfaces/memory_channel_arch.png" />

### Supported DRAM Components

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

<Steps>
  <Step title="Access the PVL database">
    Navigate to the [Qualcomm PVL](https://www.qualcomm.com/preferred-vendor-list) and sign in with your Qualcomm account.
  </Step>

  <Step title="Download the PVL file">
    Download the **QRD Hardware - Preferred Vendor List (PVL)** Excel file.
  </Step>

  <Step title="Filter for IQ-8275 memory">
    Filter by **Type: Memory** and **Chipset: IQ-8275**.
  </Step>
</Steps>

## Initialization

<img src="https://mintcdn.com/qualcomm-prod/Bh7DlgudKfjY_3Wf/Linux/images/peripheral-interfaces/ddr_initialization_sequence.png?fit=max&auto=format&n=Bh7DlgudKfjY_3Wf&q=85&s=33e13ddb947ed1741fabd66a06519fc3" width="935" height="895" data-path="Linux/images/peripheral-interfaces/ddr_initialization_sequence.png" />

<img src="https://mintcdn.com/qualcomm-prod/Bh7DlgudKfjY_3Wf/Linux/images/peripheral-interfaces/Memory_access_flow_diagram.png?fit=max&auto=format&n=Bh7DlgudKfjY_3Wf&q=85&s=46f16bf95ed44ff17eab656215fc37b4" width="1609" height="645" data-path="Linux/images/peripheral-interfaces/Memory_access_flow_diagram.png" />

## Setup and Configuration

### Prerequisites

* IQ-8275 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

<Steps>
  <Step title="Verify DRAM component">
    Confirm your DRAM part number is listed in the Qualcomm PVL for IQ-8275.
  </Step>

  <Step title="Flash the software package">
    ```bash theme={null}
    fastboot flash xbl xbl.elf
    fastboot flashall
    ```
  </Step>

  <Step title="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`
    * `Max enabled DDR Freq = 3200 MHz`
  </Step>
</Steps>

### Frequency Scaling

```bash theme={null}
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/cur_freq
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/available_frequencies
echo <frequency> > /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/userspace/set_freq
```

## Debugging

```bash theme={null}
dmesg | grep -i ddr
cat /proc/meminfo
cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/cur_freq
```

## Troubleshooting

<AccordionGroup>
  <Accordion title="DRAM Not Detected at Boot">
    **Symptoms:** No DRAM detection in UART logs; boot hangs at XBL stage.

    * Verify DRAM modules are properly seated
    * Measure VDD and VDDQ voltages — ensure they meet JEDEC specifications
    * Contact Qualcomm support if hardware is verified
  </Accordion>

  <Accordion title="DRAM Initialization Fails">
    **Symptoms:** Boot hangs after DRAM detection; training/calibration failures.

    * Check temperature and voltage stability
    * Verify signal quality on all channels
    * Try booting at a lower frequency
  </Accordion>

  <Accordion title="Performance Below Specification">
    ```bash theme={null}
    cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/cur_freq
    cat /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/governor
    cat /sys/class/thermal/thermal_zone*/temp
    ```

    Set performance governor:

    ```bash theme={null}
    echo performance > /sys/class/devfreq/soc:qcom,cpu-llcc-ddr-bw/governor
    ```
  </Accordion>
</AccordionGroup>

## Resources

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