[Macchiato] Fan control

[Matt Sealey]

According to the schematics it's on CP0_MPP48 which I do not believe
is touched by anything in EFI or Linux. There's no I2C to require,
just I assume an ability to multiplex something useful on that pin -
pinctrl driver remarks that it's got GPIO and I'm fairly sure the 8040
doesn't even have any PWM functionality (unless you count the TDM, you
could play with the frame sync..)

    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pinctrl/mvebu/pinctrl-armada-cp110.c#n466

But what you've got here is a potential for a GPIO - on or off - or
the MDIO clock for 'XG' which probably means losing an ethernet port
since you can't clock the PHY and use it for PWM.

You could write a driver that took a rapid firing timer event to
change the GPIO state, but that'd probably consume enough power and
reduce idle state residency enough to only make matters worse.

Ta,
Matt


On 6 April 2018 at 09:59, Duncan <dguthrie at posteo.net> wrote:
> Hi folks,
>
> The MacchiatoBin has a 4-pin fan header.
>
> This would suggest we could use this for fan control, over I2C (?) or
> similar.
>
> However, in the current situation, it is not possible to enable fan
> control. The pwmconfig program does not detect it, nor does lm-sensors
> find any sensors we could use to detect the current temperature on the
> device. I tried the Marvell 4.4.58 kernel, and mainline (4.15-rc2 IIRC).
>
> Does anyone have any thoughts to add?
>
> Best,
> Duncan
>
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