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Debugfs Reference

The MT7925 driver exposes debugging interfaces through the Linux debugfs filesystem.

Location

/sys/kernel/debug/ieee80211/phyN/mt76/

Find your PHY:

ls -la /sys/kernel/debug/ieee80211/
iw dev wlan0 info | grep wiphy

Available Entries

Firmware Debug (fw_debug)

Controls firmware debug logging to the host.
Permissions Read/Write (0600)
Values 0=disabled, 1=basic, 2=extended 
# Check current state
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/fw_debug

# Enable extended logging
echo 2 | sudo tee /sys/kernel/debug/ieee80211/phy0/mt76/fw_debug

# Disable logging
echo 0 | sudo tee /sys/kernel/debug/ieee80211/phy0/mt76/fw_debug

Note

Firmware debug output appears in kernel logs (dmesg). Enabling may impact performance.

Chip Reset (chip_reset)

Triggers a chip reset, optionally collecting a firmware coredump first.
Permissions Write-only (0600)
Values 0=coredump+reset (default), 1=direct reset 
# Trigger coredump + reset
echo 0 | sudo tee /sys/kernel/debug/ieee80211/phy0/mt76/chip_reset

# Direct reset without coredump
echo 1 | sudo tee /sys/kernel/debug/ieee80211/phy0/mt76/chip_reset

Viewing Coredumps:

ls /sys/class/devcoredump/

Register Access (regidx, regval)

Direct hardware register read/write access.
Permissions Read/Write (0600) 
# Set register address
echo 0xd4200 | sudo tee /sys/kernel/debug/ieee80211/phy0/mt76/regidx

# Read register value
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/regval

# Write register value
echo 0x12345678 | sudo tee /sys/kernel/debug/ieee80211/phy0/mt76/regval

Warning

Direct register access can crash the system. Use only if you understand the hardware.

TX Queues (xmit-queues)

Shows transmit queue status including DMA ring state.
Permissions Read-only (0400) 
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/xmit-queues

Output includes:

  • Queue index
  • Head/tail pointers
  • Queued packet count
  • DMA ring status

AC Queues (acq)

Shows access category queue status.
Permissions Read-only (0400) 
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/acq

RX Queues (rx-queues)

Shows receive queue status.
Permissions Read-only (0400) 
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/rx-queues

TX Statistics (tx_stats)

Shows detailed transmit statistics.
Permissions Read-only (0400) 
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/tx_stats

TX Power SKU (txpower_sku)

Shows current TX power limits per rate/band.
Permissions Read-only (0400) 
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/txpower_sku

Output includes:

  • Power limits for each MCS rate
  • Organized by band (2.4GHz, 5GHz, 6GHz)
  • Values in 0.5 dBm units

Runtime PM (runtime-pm)

Controls runtime power management.
Permissions Read/Write (0600)
Values 0=disabled, 1=enabled 
# Check current state
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/runtime-pm

# Disable runtime PM
echo 0 | sudo tee /sys/kernel/debug/ieee80211/phy0/mt76/runtime-pm

Idle Timeout (idle-timeout)

Sets the idle timeout before entering power save.
Permissions Read/Write (0600)
Values Timeout in milliseconds 
# Check current timeout
sudo cat /sys/kernel/debug/ieee80211/phy0/mt76/idle-timeout

# Set to 100ms
echo 100 | sudo tee /sys/kernel/debug/ieee80211/phy0/mt76/idle-timeout

Tracepoints

If CONFIG_MT76_TRACER is enabled:

# Enable all mt76 tracepoints
echo 1 | sudo tee /sys/kernel/debug/tracing/events/mt76/enable

# View trace
cat /sys/kernel/debug/tracing/trace

Available tracepoints:

  • mt76:dev_irq - Interrupt events
  • mt76:tx - TX events
  • mt76:rx - RX events
  • mt76:mcu_msg - MCU messages