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From: Chris Packham <chris.packham@alliedtelesis.co.nz>
To: jdelvare@suse.com,
	linux@roeck-us.net,
	robh@kernel.org,
	krzk+dt@kernel.org,
	conor+dt@kernel.org,
	ukleinek@kernel.org
Cc: linux-hwmon@vger.kernel.org,
	devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-pwm@vger.kernel.org,
	Chris Packham <chris.packham@alliedtelesis.co.nz>
Subject: [PATCH v4 0/3] hwmon: (adt7475) duty cycle configuration
Date: Wed, 29 May 2024 10:56:35 +1200
Message-ID: <20240528225638.1211676-1-chris.packham@alliedtelesis.co.nz>
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I have a system that has very over spec'd fans so the amount of noise whe=
n they
run at 100% duty cycle is considerable. We have userspace monitoring tool=
s that
will configure appropriate fan control parameters but there is a bit of a=
 delay
between the kernel loading the driver and the userland tools catching up =
to
configure the fan control. This series adds device properties that allow =
the
PWM duty cycle to be specified via device properties so the PWM duty cycl=
e can
be reduced as soon as possible.

This series attempts to setup the adt7475 as a pwm provider so that we ca=
n
specify these properties. The devicetree support was reasonably straight
forward (example usage is in the binding patch). I struggled to get the A=
CPI
version working well and in the end the code had to distinguish between t=
he
of_node and other case. The ASL I've ended up with is

    Device (ADT0)
    {
        Name (_HID, "PRP0001")
        Name (_CRS, ResourceTemplate () {
            I2cSerialBusV2 (0x2E, ControllerInitiated,
                            100000, AddressingMode7Bit,
                            "^^CH00", 0x00,
                            ResourceConsumer, , Exclusive, )
        })
        Name (_DSD, Package () {
            ToUUID (UUID_DEVICE_PROPERTIES),
            Package () {
                Package () { "compatible", "adi,adt7476" },
                Package () { "#pwm-cells", 4 },
            },
        })
        Device (FAN0)
        {
            Name (_ADR, 0)
            Name (_DSD, Package () {
                ToUUID (UUID_DEVICE_PROPERTIES),
                Package () {
                    Package () { "pwms", Package () { 0, 22500, 1, 50 } }=
,
                }
            })
        }
        Device (FAN1)
        {
            Name (_ADR, 0)
            Name (_DSD, Package () {
                ToUUID (UUID_DEVICE_PROPERTIES),
                Package () {
                    Package () { "pwms", Package () { 2, 22500, 1, 50 } }=
,
                }
            })
        }
    }

If had to introduce a code path that parses that because try as I might I=
 could
not convince fwnode_property_get_reference_args() to fetch the informatio=
n out
of the ACPI data. If I've missed something obvious please let me know.

Chris Packham (3):
  dt-bindings: hwmon: Add adt7475 fan/pwm properties
  dt-bindings: hwmon: adt7475: Deprecate adi,pwm-active-state
  hwmon: (adt7475) Add support for configuring initial PWM state

 .../devicetree/bindings/hwmon/adt7475.yaml    |  27 ++++-
 drivers/hwmon/adt7475.c                       | 112 ++++++++++++++++++
 2 files changed, 137 insertions(+), 2 deletions(-)

--=20
2.45.1