mt7915e: MT7916 temp1_input intermittently reports 491 °C or 0 °C on both bands (fw 20240823)

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
28/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
c, linux
Domain
embedded-iot, networking

Research direction

The symptom is in the mt7915e driver's hwmon temperature reading for the MT7916 phys (phy0 and phy1), which the MCU firmware query returns. Start by reproducing with sensors -u on repeated pulls and comparing against the MT7986 phy2 reading. Done would mean the MT7916 reading stays plausible or the driver rejects the invalid value. Needs firmware and hardware knowledge, so a maintainer should confirm the approach first.

Written by the indexing model from the issue text.

Description

Device / versions
  • Board: Acer Connect Vero W6m (acer,vero-w6m), mediatek/filogic
  • SoC radio: MT7986A — phy2, 5 GHz (mt798x-wmac 18000000.wifi)
  • PCIe radio: MT7916 DBDC — phy0 2.4 GHz, phy1 6 GHz (mt7915e 0000:01:00.0)
  • OpenWrt 25.12.6 r33311-981c978eff, kernel 6.12.112
  • mt76: 2026.03.19~39c960c3-r3 (kmod-mt7915e, kmod-mt7916-firmware)
  • MT7916 firmware (from dmesg):
    • HW/SW Version: 0x8a108a10, Build Time: 20240823172725a
    • WM Firmware Version: ____000000, Build Time: 20240823172741
    • WA Firmware Version: DEV_000000, Build Time: 20240823172837
  • wed_enable=N
Problem

The hwmon temperature of the MT7916 (phy0 and phy1) intermittently reads 491 °C
or 0 °C. Readings a few seconds apart alternate between the two, and both
phys always show the identical bogus value. The MT7986 radio (phy2) reads
normally at the same time.

# sensors -u   (pull 1)
mt7915_phy1-pci-0100     temp1_input: 491.000
mt7915_phy2-isa-18000000 temp1_input: 42.000
mt7915_phy0-pci-0100     temp1_input: 491.000

# sensors -u   (pull 2, seconds later)
mt7915_phy1-pci-0100     temp1_input: 0.000
mt7915_phy2-isa-18000000 temp1_input: 42.000
mt7915_phy0-pci-0100     temp1_input: 0.000

# sensors -u   (pull 3)
mt7915_phy1-pci-0100     temp1_input: 491.000
mt7915_phy0-pci-0100     temp1_input: 491.000

No "Retry message" or MCU timeout messages appear in dmesg.

So the MT7916 firmware's sensor query seems to return invalid data
intermittently. 20240823 appears to be the latest public MT7916 firmware.

Possibly related but different: #729 reports a constant offset on the MT7986's
built-in radio (MT7975 front-end), with plausible values. Here the MT7986 radio
reads correctly, and the MT7916 returns impossible values (491/0) intermittently.

Dominant language
C
Stars
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Forks
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