system-monitor-graph@rcassani: Add CPU fan monitoring

[karthikmudaliarX]

What

• add CPU Fan as its own selectable graph under the CPU variables
• show the current RPM with a green On state, and a clean red Off state without a misleading 0 RPM value
• use a slightly smaller RPM readout so four-digit fan speeds fit comfortably
• normalize RPM to a fixed 0–4000 graph range and reuse the standard single-series renderer
• prefer CPU/processor-labelled sensors, with a conservative Dell/ThinkPad primary-fan fallback
• rediscover stale hwmon paths after read failures and retry initial discovery with capped backoff when the driver is not ready yet
• update desklet metadata, documentation, the combined screenshot, and gettext catalogs

Why

A separate graph makes fan activity over time visible without mixing RPM into the CPU-temperature scale. Conservative sensor selection avoids mislabelling arbitrary chassis, GPU, PSU, or pump fans.

Screenshot

Captured on Linux Mint 22.3 / Cinnamon 6.6.7 using the dell_smm hwmon driver.

Verification

• node --check system-monitor-graph@rcassani/files/system-monitor-graph@rcassani/desklet.js
• GJS/CJS parser check
• ./validate-spice system-monitor-graph@rcassani
• JSON validation and msgfmt --check for every translated catalog
• translation-preservation check to reject incorrect fuzzy matches
• git diff --check
• live hardware smoke tests for real positive-RPM and stopped-fan states; the installed source is sensor-backed

Known limitation

The repository has no automated Cinnamon desklet test harness for sysfs sensor variants. Zero, positive, missing, stale-path, and delayed-driver behavior were reviewed and hardware-smoke-tested but are not covered by unit tests. RPM values above 4000 remain numerically accurate but are clipped at the graph ceiling by design.

cc @rcassani

[rcassani]

I do not have the hardware to test this. Please provide some screenshots for of the desklet looks with this addition.

In other thought, the fan status-speed is a variable, to me it makes more sense to have it's on graph, with the title:

"CPU Fan speed xxx RPM [spaces] 🟢 On / 🔴 Off",

then it would be possible to also see the history of the activity of the fan.

[karthikmudaliarX]

@rcassani how does it look now

[rcassani]

Hi @karthikmudaliarX, thank you so much for this feature, it is looking great. Please find here some of my comments, after addressing this is should be good to be merged.

[rcassani]

@karthikmudaliarX, for some reason this comment was not published in the previous review

[claudiux]

Please resolve all conversations.

[claudiux]

@rcassani Is all that OK for you?

[rcassani]

@claudiux,

• The PR is ready once this small typo is addressed
• I do not have the hardware to test any of the options for CPU Fan detection. The code works well without Fan reported in hwmon
• If @karthikmudaliarX confirms the two options for CPU Fan detection are working properly the PR can be merged

Thank you both!

[rcassani]

The change in the desklet settings was overseen:
Fan Speed --> Fan

[karthikmudaliarX]

Fixed the settings label from Fan Speed to Fan.

For the hardware check, I’ve only been able to validate the Dell dell_smm fallback on my laptop. I tested it with the fan both running and stopped, and it works correctly. My machine doesn’t expose a CPU/processor-labelled fan sensor, so I haven’t been able to test that detection path on actual hardware.

Thanks for the review!

[rcassani]

@claudiux this is ready to be merged, thanks