Re: [PATCH v2] hwmon: add a driver for the temp/voltage sensor on PolarFire SoC

[Guenter Roeck <linux@roeck-us.net>]

On 6/9/26 02:43, Conor Dooley wrote:
> On Mon, Jun 08, 2026 at 10:03:48AM -0700, Guenter Roeck wrote:
>> On 6/3/26 06:19, Conor Dooley wrote:
>>> From: Lars Randers <lranders@mail.dk>
>>>
>>> Add a driver for the temperature and voltage sensors on PolarFire SoC.
>>> The temperature reports how hot the die is, and the voltages are the
>>> SoC's 1.05, 1.8 and 2.5 volt rails respectively.
>>>
>>> The hardware supports alarms in theory, but there is an erratum that
>>> prevents clearing them once triggered, so no support is added for them.
>>>
>>> The hardware measures voltage with 16 bits, of which 1 is a sign bit and
>>> the remainder holds the voltage as a fixed point integer value. It's
>>> improbable that the hardware will work if the voltages are negative, so
>>> the driver ignores the sign bits.
>>>
>>> There's no dt support etc here because this is the child of a simple-mfd
>>> syscon.
>>>
>>> Signed-off-by: Lars Randers <lranders@mail.dk>
>>> Co-developed-by: Conor Dooley <conor.dooley@microchip.com>
>>> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
>>
>> Comments inline.
> 
> Cheers.
> 
...
>>
>> If regmap never returns errors this needs to be documented in the driver.
> 
> It's an mmio regmap via a syscon, it evaluates to readl()/writel() so
> there's nothing that can fail /and/ return an error.
> I mean, I can add if (ret) return ret, there's not a clean place to put
> a comment about it I don't think.
> 

No, there is no need to add dummy error checks.  Just add a comment
either at the top of the driver or maybe even better where the regmap
is initialized and explain the above.

Guenter