Hi Guenter,
> From: Nuno Sá <nuno.sa@xxxxxxxxxx>
> Sent: Thursday, July 8, 2021 2:01 PM
> To: linux-hwmon@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>; Rob Herring
> <robh+dt@xxxxxxxxxx>; Jean Delvare <jdelvare@xxxxxxxx>
> Subject: [RFC PATCH 0/6] AXI FAN new features and improvements
>
> This series adds some new features to the axi-fan-control driver. On
> top
> of that, the HW had some changes (basically it now starts automatically
> out of reset) so that the driver needed some minor refactoring. The
> reason I'm sending this as RFC, is mainly because of the last patch
> ("hwmon: axi-fan-control: support temperature vs pwm points"). The
> core
> has some predefined values which define a temperature vs pwm
> curve [1].
> It also exposes registers so that users can change it according to their
> needs. As I could not find standard attributes in the subsystem, I'm
> proposing some "raw" sysfs files. Looking at [2], the pwm_auto_point
> stuff looked to be what I want. Obviously I might be wrong :). If this
> is accepted, I will add a proper sysfs DOC file describing the new files
> (being lazy in the RFC).
>
> For patch 5 ("hwmon: axi-fan-control: clear the fan fault irq at
> startup"),
> it's also arguable if we really need it. The main reason I have it is
> because of some userland apps that might take some drastic measures
> by
> just reading 1 fan_fault alarm. Obviously, we can argue that the
> problem
> is in the app and not in the driver. Though it's such a minimal change
> that I decided to include it (I'm more than fine in dropping the patch).
>
> [1]: https://wiki.analog.com/resources/fpga/docs/axi_fan_control
> [2]:
> https://urldefense.com/v3/__https://www.kernel.org/doc/Documen
> tation/hwmon/sysfs-
> interface__;!!A3Ni8CS0y2Y!uwjpaOT8QEBVfKTCWELJNbjJJ69iR7S3tKS
> WV4B0K742CtcARkTtAqMxknnpPw$
>
> Nuno Sá (6):
> hwmon: axi-fan-control: make sure the clock is enabled
> hwmon: axi-fan-control: add tacho devicetree properties
> dt-bindings: axi-fan-control: add tacho properties
> hwmon: axi-fan-control: handle irqs in natural order
> hwmon: axi-fan-control: clear the fan fault irq at startup
> hwmon: axi-fan-control: support temperature vs pwm points
>
The HW guy is willing to change how the core works. This means,
that all that unstable pwm - rpm points will go away and we will
have a register where we can set the minimum fan speed for
evaluating the FAN. He also said that the default value for the
this setting will be pretty low so that we should only have _real_
faults at startup which means patch 5 should not be needed
anymore...
Anyways, I will send a new pull with patches 1,3 and 5 and
as soon as I have some HW ready to test, I will send the other
patches. With the new mechanism, we can also simplify the IRQ
handling [1]...
For the new devicetree property, I think now it really is a fan
property which makes me wonder if the property will be accepted
in the controller bindings or if I need to send a fan.yaml...
[1]: https://elixir.bootlin.com/linux/v5.14-rc3/source/drivers/hwmon/axi-fan-control.c#L280
- Nuno Sá
