Is this a disk activitiy indicator?
Thanks for any help
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Congrats! That is the “everything’s OK” light. I think it’s kinda neat, reminds me of an aircraft navigation light. But seriously though, I am also curious about the lights and how they are controlled. I’ve noticed that mine comes on about midway through the booting process, seems like it is responding to something in the OS…watchdog perhaps?
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Digging through the schematics (v1.2a) the green status LED is connected via a small mosfet to STS_PWR on the board, which in turn is driven by RGPIO3 from the JH7110.
The datasheet doesnt help much, except to list it as a System Signal pin. And the Technical Documentation is not yet very helpful.
But it is obvious that the RGPIO lines are different from the GPIO lines, and used by the system itself, the only ones documented are RGPIO[012] which are used to select boot modes. Pin 0 is pulled low, in turn making the system select the boot mode using pins 1 and 2, which are connected to the Boot Mode dip switch.
I’m sure it will become clearer with time.
Edit: As you say, this must be related to the Watchdog features of the JH7110, but the documentation for that is minimal too.
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It means whatever you want it to mean.
The led is managed by the kernel’s led subsystem. Cat this file /sys/class/leds/ack/trigger to see the possible triggers, and which one is currently selected. More triggers can be obtained by loading modules or rebuilding the kernel.
echo "heartbeat" >/sys/class/leds/ack/trigger to set the trigger to a heartbeat event, which is the default.
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To me it looks like it is controlled by bit 6 of the PMU_HARD_EVENT and is possibly toggled on and off by a hardware interrupt in the JH7110, if the hardware event is enabled - which it is by default. (ref: Hard_event_6_on_mask and https://github.com/starfive-tech/linux/blob/JH7110_VisionFive2_devel/include/soc/starfive/jh7110_pmu.h#L67 )
Since it is part of the Power Management Unit inside the JH7110, it might be indicating something about power, possibly that the JH7110 has power and is functioning. But since RGPIO0 and RGPI1 are used to read where the hardware should load the SPL (Second Program Loader) from, in reality it could be indicating anything at all. But in this context I suspect that the solid red LED is indicating that there is some source of power and the flashing green LED is indicating that there is at least enough power for the JH7110 to generate and process hardware interrupts once it has reached far enough into the boot process.
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On the schematic the red led is driven (again via mosfet) by the VDD18_AON line, which is one of the control outputs from the AXP15060 power controller (PMIC).
As well as controlling the red power LED this signal also seems to enable the PCIE M.2, and a lot of other peripherals, I didn’t dig too deep. It also provides the pullup voltage for the boot dip switch.
So, for the red led I’m guessing it turns on at the point where the firmware enables the storage systems and selects which one to boot from. It is not user controllable.l
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