The newly added variable is only used in an #if block:

drivers/hwmon/max6650.c: In function 'max6650_probe':
drivers/hwmon/max6650.c:766:33: error: unused variable 'cooling_dev' [-Werror=unused-variable]

Change the #if to if() so the compiler can see what is actually
going on.

Fixes: a8463754a5a9 ("hwmon: (max6650) Use devm function to register thermal device")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

CHECK: struct mutex definition without comment
CHECK: Alignment should match open parenthesis

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Pass errors from i2c_smbus_read_byte_data() back to the caller of
max6650_update_device().

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Only tachometer and alarm status registers are modified by the chip.
All other registers only need to be read only once, and reading them
repeatedly does not add any value.

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Convert driver to use devm_hwmon_device_register_with_info to simplify
the code and to reduce its size.

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Instead of re-reading the alarm register after reporting an alarm,
mark cached values as invalid. While this results in always reading all
data on subsequent reads, it is quite unlikely that such reads will
actually happen before the cache times out. The upside is avoiding
unnecessary unconditional i2c read operations.

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

The alarm_en register is read each time the is_visible function is called.
Since it is a configuration register, this is completely unnecessary.
Read it once and cache its value.

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Declare valid as boolean to match its use case.

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Do not overwrite errors reported from i2c functions, and don't ignore
any errors.

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Consolidate conversion from pwm value to dac value and from dac value
to pwm value into helper functions.

While doing this, only update the cached dac value if writing it
to the chip was successful after an update. Also, put macro argument
of DIV_FROM_REG() into (), and simplify return statement of
max6650_set_cur_state().

Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>