[RFC PATCH] hwmon: remove tautological dependency expressions from Kconfig

[RFC PATCH] hwmon: remove tautological dependency expressions from Kconfig

[Laszlo Ersek]

Commit 554b3529fe01 ("thermal/drivers/core: Remove the module Kconfig's
option") [1] obviated some of the "Optional dependencies" (as described in
"Documentation/kbuild/kconfig-language.rst") in "drivers/hwmon/Kconfig".

Namely, said commit restricted the valid/possible subset of the full
Cartesian product "CONFIG_THERMAL x CONFIG_THERMAL_OF" to

  { (n, n), (y, n), (y, y) }

through "drivers/thermal/Kconfig". Numerically (using tristate values),
this set can be expressed as:

  { (0, 0), (2, 0), (2, 2) }

Over this set, the "drivers/hwmon/Kconfig" tristate expression

  THERMAL || !THERMAL_OF

or equivalently,

  max(THERMAL, 2-THERMAL_OF)

invariably evaluates to "y" (2).

Similarly, with THERMAL having been restricted to

  { n, y }

or numerically,

  { 0, 2 }

the "drivers/hwmon/Kconfig" tristate expression

  THERMAL || THERMAL=n

or equivalently,

  max(THERMAL, THERMAL=0)

invariably evaluates to "y" (2). (Note that "THERMAL=0" returns either "y"
(2) or "n" (0).)

Commit f37353320ee9 ("hwmon/drivers/core: Simplify complex dependency")
[2], which is the final commit of the series that [1] is the beginning of,
cleaned up the hwmon C source code in fact; however, it missed the
now-collapsed dependencies in Kconfig. At the time of [2], six of today's
such dependencies were present in Kconfig. Since then, two more have been
added (such that they persist, anyway): one by commit 4f8d374b770a
("hwmon: (max6650) add thermal cooling device capability"), which was
independent of the above-noted series, and another by commit 9855caf5d4eb
("hwmon: add driver for the hwmon parts of qnap-mcu devices"), which was a
descendant of the series.

Remove these always-"y" dependencies.

Cc: Andrew Jeffery <andrew@codeconstruct.com.au>
Cc: Cristian Marussi <cristian.marussi@arm.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Sudeep Holla <sudeep.holla@kernel.org>
Cc: arm-scmi@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-aspeed@lists.ozlabs.org
Cc: linux-hwmon@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Laszlo Ersek <laszlo.ersek@arm.com>
---

Notes:
    Untested (hence RFC) -- I don't know how to regression-test this patch
    comprehensively yet minimally.

 drivers/hwmon/Kconfig | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 2bfbcc033d59..d3a9c8a3a79c 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -403,7 +403,6 @@ config SENSORS_ARCTIC_FAN_CONTROLLER
 config SENSORS_ARM_SCMI
 	tristate "ARM SCMI Sensors"
 	depends on ARM_SCMI_PROTOCOL
-	depends on THERMAL || !THERMAL_OF
 	help
 	  This driver provides support for temperature, voltage, current
 	  and power sensors available on SCMI based platforms. The actual
@@ -415,7 +414,6 @@ config SENSORS_ARM_SCMI
 config SENSORS_ARM_SCPI
 	tristate "ARM SCPI Sensors"
 	depends on ARM_SCPI_PROTOCOL
-	depends on THERMAL || !THERMAL_OF
 	help
 	  This driver provides support for temperature, voltage, current
 	  and power sensors available on ARM Ltd's SCP based platforms. The
@@ -435,7 +433,6 @@ config SENSORS_ASB100
 config SENSORS_ASPEED
 	tristate "ASPEED AST2400/AST2500 PWM and Fan tach driver"
 	depends on ARCH_ASPEED || COMPILE_TEST
-	depends on THERMAL || THERMAL=n
 	select REGMAP
 	help
 	  This driver provides support for ASPEED AST2400/AST2500 PWM
@@ -788,7 +785,6 @@ config SENSORS_G762
 config SENSORS_GPIO_FAN
 	tristate "GPIO fan"
 	depends on GPIOLIB || COMPILE_TEST
-	depends on THERMAL || THERMAL=n
 	help
 	  If you say yes here you get support for fans connected to GPIO lines.
 
@@ -1357,7 +1353,6 @@ config SENSORS_MAX6639
 config SENSORS_MAX6650
 	tristate "Maxim MAX6650 sensor chip"
 	depends on I2C
-	depends on THERMAL || THERMAL=n
 	help
 	  If you say yes here you get support for the MAX6650 / MAX6651
 	  sensor chips.
@@ -1732,7 +1727,6 @@ config SENSORS_PC87427
 config SENSORS_NTC_THERMISTOR
 	tristate "NTC thermistor support"
 	depends on IIO
-	depends on THERMAL || !THERMAL_OF
 	help
 	  This driver supports NTC thermistors sensor reading and its
 	  interpretation. The driver can also monitor the temperature and
@@ -1933,7 +1927,6 @@ config SENSORS_PT5161L
 config SENSORS_PWM_FAN
 	tristate "PWM fan"
 	depends on PWM || COMPILE_TEST
-	depends on THERMAL || THERMAL=n
 	help
 	  If you say yes here you get support for fans connected to PWM lines.
 	  The driver uses the generic PWM interface, thus it will work on a
@@ -1945,7 +1938,6 @@ config SENSORS_PWM_FAN
 config SENSORS_QNAP_MCU_HWMON
 	tristate "QNAP MCU hardware monitoring"
 	depends on MFD_QNAP_MCU
-	depends on THERMAL || THERMAL=n
 	help
 	  Say yes here to enable support for fan and temperature sensor
 	  connected to a QNAP MCU, as found in a number of QNAP network

Re: [RFC PATCH] hwmon: remove tautological dependency expressions from Kconfig

[sashiko-bot]

> Commit 554b3529fe01 ("thermal/drivers/core: Remove the module Kconfig's
> option") [1] obviated some of the "Optional dependencies" (as described in
> "Documentation/kbuild/kconfig-language.rst") in "drivers/hwmon/Kconfig".
> 
> Namely, said commit restricted the valid/possible subset of the full
> Cartesian product "CONFIG_THERMAL x CONFIG_THERMAL_OF" to
> 
>   { (n, n), (y, n), (y, y) }
> 
> through "drivers/thermal/Kconfig". Numerically (using tristate values),
> this set can be expressed as:
> 
>   { (0, 0), (2, 0), (2, 2) }
> 
> Over this set, the "drivers/hwmon/Kconfig" tristate expression
> [ ... ]
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-aspeed@lists.ozlabs.org
> Cc: linux-hwmon@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Laszlo Ersek <laszlo.ersek@arm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260729215436.2103380-1-laszlo.ersek@arm.com?part=1

Re: [RFC PATCH] hwmon: remove tautological dependency expressions from Kconfig

[Guenter Roeck]

On 7/29/26 14:54, Laszlo Ersek wrote:
> Commit 554b3529fe01 ("thermal/drivers/core: Remove the module Kconfig's
> option") [1] obviated some of the "Optional dependencies" (as described in
> "Documentation/kbuild/kconfig-language.rst") in "drivers/hwmon/Kconfig".
> 
> Namely, said commit restricted the valid/possible subset of the full
> Cartesian product "CONFIG_THERMAL x CONFIG_THERMAL_OF" to
> 
>    { (n, n), (y, n), (y, y) }
> 
> through "drivers/thermal/Kconfig". Numerically (using tristate values),
> this set can be expressed as:
> 
>    { (0, 0), (2, 0), (2, 2) }
> 
> Over this set, the "drivers/hwmon/Kconfig" tristate expression
> 
>    THERMAL || !THERMAL_OF
> 
> or equivalently,
> 
>    max(THERMAL, 2-THERMAL_OF)
> 
> invariably evaluates to "y" (2).
> 
> Similarly, with THERMAL having been restricted to
> 
>    { n, y }
> 
> or numerically,
> 
>    { 0, 2 }
> 
> the "drivers/hwmon/Kconfig" tristate expression
> 
>    THERMAL || THERMAL=n
> 
> or equivalently,
> 
>    max(THERMAL, THERMAL=0)
> 
> invariably evaluates to "y" (2). (Note that "THERMAL=0" returns either "y"
> (2) or "n" (0).)
> 
> Commit f37353320ee9 ("hwmon/drivers/core: Simplify complex dependency")
> [2], which is the final commit of the series that [1] is the beginning of,
> cleaned up the hwmon C source code in fact; however, it missed the
> now-collapsed dependencies in Kconfig. At the time of [2], six of today's
> such dependencies were present in Kconfig. Since then, two more have been
> added (such that they persist, anyway): one by commit 4f8d374b770a
> ("hwmon: (max6650) add thermal cooling device capability"), which was
> independent of the above-noted series, and another by commit 9855caf5d4eb
> ("hwmon: add driver for the hwmon parts of qnap-mcu devices"), which was a
> descendant of the series.
> 
> Remove these always-"y" dependencies.
> 

Dependencies such as "THERMAL || THERMAL=n" were supposed to enable the
driver to be built as module or into the kernel if THERMAL=n, and to
force it to be built as module if THERMAL=m. However, both THERMAL
and THERMAL_OF are boolean, so this really does not make sense.

Applied.

Thanks,
Guenter