ingenic: restore the temperature HAL wiring, and report degrees not millidegrees

[widgetii]

ingenic_get_temp() has been dead code since May 2023.

6e697a7 ("[INGENIC] Fix enable sensor clock") deleted the two lines in
setup_hal_ingenic() that assigned hal_temperature behind the same
access() guard the allwinner, rockchip, novatek, fh and gm HALs use. The
subject of that commit was the sensor clock; the deletion looks like collateral.

Nothing reported it, and that is the interesting part: no Ingenic SoC up to and
including T40 has a die temperature sensor, so no Ingenic kernel registers a
thermal zone, so the guard would have left hal_temperature NULL anyway. -t
answered "Temperature cannot be retrieved" before this change and answers it
after. The wiring is restored because it is the shape every sibling HAL has —
a kernel that ever grows a zone then needs no change here — and because a
function no caller can reach is a trap for the next reader.

Being unreachable, it had also kept two bugs:

• it returned the sysfs value verbatim, where every sibling divides by 1000, so
  a 45 °C chip would have been reported as 45000;
• on a failed read it returned -237.0, which -t would have printed as a
  temperature instead of letting gethwtemp()'s NAN produce the honest error.

Verification

Builds, all four as CI does them: native, arm32 (hi3516cv100 musleabi), mips32
(ingenic-t31 musl) and arm64 (Bootlin aarch64 musl) — clean, no new warnings.
cYAML_test and reginfo_test pass; tools/test_pipeline.sh passes.

On hardware — lab T31 (T31L, SC2332, kernel 3.10.14__isvp_swan_1.0__), mips32
build copied to the camera:

--- stock ipcinfo --temp:
Temperature cannot be retrieved
rc=1
--- patched --temp:
Temperature cannot be retrieved
rc=1
--- patched chip name:
t31l

Unchanged, as intended. /sys/class/thermal does not exist on that board at
all — with CONFIG_THERMAL off the class is never registered — so the guard is
what keeps --temp honest, and the reader itself cannot be exercised there.
It was exercised instead against a real zone through libipchw on the build
host: 27800 → 27.80, and with the zone hidden under unshare -rm plus a
tmpfs over /sys/class/thermal → NAN.

Note

The same dead -237.0 sentinel is in novatek.c, fh.c, gm.c,
allwinner.c and rockchip.c. It is near-unreachable there too (the access()
guard, and /1000 turns it into -0.237), so it is left alone here rather than
widening this diff — happy to sweep it separately if wanted.

[qodo-free-for-open-source-projects]

PR Summary by Qodo

Restore Ingenic temperature HAL wiring and report degrees Celsius

🐞 Bug fix 🕐 10-20 Minutes

AI Description

• Restore guarded temperature callback registration so Ingenic can use a thermal zone when
 available.
• Convert sysfs millidegrees to degrees Celsius and return NAN when reading fails.
• Preserve the existing unavailable-temperature response on devices without a thermal zone.

Diagram

graph TD
  CLI["Temperature CLI"] --> HW["gethwtemp"] --> Reader["Ingenic reader"] --> Sysfs[("Thermal sysfs")]
  Setup["Ingenic setup"] -->|checks readability| Sysfs
  Setup -->|registers if readable| Reader

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High-Level Assessment

Keep the guarded registration: it matches sibling HALs and preserves the current behavior on Ingenic devices without a thermal zone. Unconditional registration could rely on the reader returning NAN, but would discard that established availability check without a clear benefit.

Files changed (1) +16 / -6

Bug fix (1) +16 / -6

ingenic.cRestore guarded temperature registration and correct reader results +16/-6

Restore guarded temperature registration and correct reader results

• Registers ingenic_get_temp when the thermal-zone temperature entry is readable. The reader now converts millidegrees to degrees Celsius and returns NAN instead of a printable sentinel when the read fails.

src/hal/ingenic.c

[qodo-free-for-open-source-projects]

Code Review by Qodo

🐞 Bugs (0) 📘 Rule violations (0) 📎 Requirement gaps (0)

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