Memory and Storage - Qualcomm Dragonwing Documentation

The Qualcomm Linux platform supports four primary storage types.

Storage Type	Versions
Universal Flash Storage (UFS)	v2.1, v2.2, v3.1
Embedded Multi-Media Card (eMMC)	v5.1
Non-Volatile Memory Express (NVMe)	v1.3
Secure Digital (SD) Card	v3.0

Configure the device to boot from only one storage source. Using both sources for bootable files may cause system crashes or unpredictable behavior.

UFS Storage

Features

Feature	Description
Lanes	2 lanes supported
Gear	HS Gear 1, 2, 3, and 4
Low-Power Mode	Link hibernate and device sleep
Hot-Plug	Not supported (embedded only)

Power Management States

Auto-Hibern8 (AH8) — Transitions PHY link to Hibernate after 150 ms of idle time (adjustable).

cat /sys/devices/platform/soc@0/1d84000.ufs/auto_hibern8

Clock Gating — Enabled by default.

cat /sys/devices/platform/soc@0/1d84000.ufs/clkgate_enable
echo 0 > /sys/devices/platform/soc@0/1d84000.ufs/clkgate_enable  # Disable for debugging

Clock Scaling — Enabled by default; disabling increases power consumption.

cat /sys/devices/platform/soc@0/1d84000.ufs/clkscale_enable

UFS Provisioning

Set bConfigDescrLock="0" during development. Set to "1" after finalization to prevent reprovisioning.

Default Partition Layout:

LUN0 — Linux data and filesystem images
LUN1 & LUN2 — Boot WLUN (0xB0) alternates for fail-safe XBL backup
LUN4 — Rest of boot chain
LUN6 & LUN7 — Unused by default

Architecture Diagrams

eMMC Storage

Features

Feature	Description
Speed	DDR50, HS200, HS400, HS400 Enhanced
Sleep Mode	Clock gating and auto suspend
Command Queuing	Multiple simultaneous commands

Device Tree Configuration

&sdhc_1 {
    status = "okay";
    pinctrl-names = "default", "sleep";
    pinctrl-0 = <&sdc1_on>;
    pinctrl-1 = <&sdc1_off>;
    vmmc-supply = <&vreg_l19a_2p9>;
    vqmmc-supply = <&vreg_l12a_1p8>;
};

SD Card Storage

Feature	Description
Bus Width	4-bit mode
Speed	SDR50, SDR104, DDR50
Hot-Plug	Supported

NVMe Storage

Feature	Description
Lanes	4 lanes over PCIe port (PCIe1)
Interface	High-speed serial

Configuration Guide

Mount File Systems

UFS / eMMC
SD Card
NVMe

mkdir /tmp/data
mount -t ext4 /dev/sda3 /tmp/data
df -a

mkdir sdcard
mkfs.vfat /dev/mmcblk1p1
mount -t vfat /dev/mmcblk1p1 /sdcard
df -a

fdisk /dev/nvme0n1
reboot
mkfs.ext4 /dev/nvme0n1p1
mount /dev/nvme0n1p1 /media
df -a

Power Management Control

mount -t debugfs none /sys/kernel/debug

# UFS Auto-Hibern8
echo <value_in_us> > /sys/devices/platform/soc@0/1d84000.ufs/auto_hibern8

# UFS Clock Gating
echo 0 > /sys/devices/platform/soc@0/1d84000.ufs/clkgate_enable  # Disable
echo 1 > /sys/devices/platform/soc@0/1d84000.ufs/clkgate_enable  # Enable

Troubleshooting

Command Pending in Device

Symptoms: ufshcd_abort: cmd pending in the deviceContact UFS device vendor; check device compatibility and power supply stability.

No Response from Device

Symptoms: ufshcd_abort: no response from device, err -110Check physical connections, verify power rails, check PHY initialization.

Physical Adapter / Data Link Error

mount -t debugfs none /sys/kernel/debug
cat /sys/kernel/debug/ufshcd/1d84000.ufs/stats

Indicates poor signal quality. Check PCB layout and PHY settings.

Unhandled SMMU Fault

In the ufshc_mem node in the SoC DTSI file, change:

qcom,iommu-dma = "fastmap";

to:

qcom,iommu-dma = "bypass";

Command Reference

UFS Commands

Purpose	Command
Check PA/DL error count	`cat /sys/kernel/debug/ufshcd/1d84000.ufs/stats`
Read current clock frequency	`cat /sys/devices/platform/soc@0/1d84000.ufs/devfreq/1d84000.ufs/cur_freq`
Read device state	`cat /sys/devices/platform/soc@0/1d84000.ufs/power_info/dev_pm`
Read link state	`cat /sys/devices/platform/soc@0/1d84000.ufs/power_info/link_state`
Read runtime status	`cat /sys/devices/platform/soc@0/1d84000.ufs/power/runtime_status`

eMMC Commands

Purpose	Command
Error stats	`cat /sys/kernel/debug/mmc0/err_stats`
Current clock	`cat /sys/kernel/debug/mmc0/clock`
Runtime status	`cat /sys/devices/platform/soc@0/87c4000/power/runtime_status`

For IQ-8275, the eMMC address is 87c4000.

References

EXT4 Filesystem Introduction

​UFS Storage

​Features

​Power Management States

​UFS Provisioning

​Architecture Diagrams

​eMMC Storage

​Features

​Device Tree Configuration

​SD Card Storage

​NVMe Storage

​Configuration Guide

​Mount File Systems

​Power Management Control

​Troubleshooting

​Command Reference

​UFS Commands

​eMMC Commands

​References

UFS Storage

Features

Power Management States

UFS Provisioning

Architecture Diagrams

eMMC Storage

Features

Device Tree Configuration

SD Card Storage

NVMe Storage

Configuration Guide

Mount File Systems

Power Management Control

Troubleshooting

Command Reference

UFS Commands

eMMC Commands

References