linux-kernel - Re: hwmon: (adt7475) Add support for inverting pwm output

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Message-ID: <e398560f-f8d1-afbc-4aae-ab3cf2555e8e@alliedtelesis.co.nz>
Date:   Tue, 18 Apr 2023 20:41:32 +0000
From:   Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To:     Mariusz Białończyk <manio@...boo.net>
CC:     "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: hwmon: (adt7475) Add support for inverting pwm output

Hi Marius,

+cc linux-hwmon, lkml

On 18/04/23 23:06, Mariusz Białończyk wrote:
> Hi Chris,
> I discovered by accident that my dmesg is telling me:
> [Mon Apr 17 19:08:59 2023] adt7475 19-002e: Error configuring pwm polarity
> [Mon Apr 17 19:08:59 2023] adt7475 19-002e: ADT7473 device, revision 1
>
> motherboard:
> DMI: System manufacturer System Product Name/M4A785TD-V EVO, BIOS 2105    07/23/2010
>
> Is this something i need to be afraid, or it's nothing serious?

It's probably harmless, unless your board is intentionally setting the 
pwm-active-state (which I suspect it won't be as your BIOS is probably 
taking care of that if required). I suspect it's more a case of the code 
not handling the absence of a device tree which the check for -EINVAL 
was supposed to deal with. There's an outside chance that there is a 
problem on the I2C bus but that would require your platform to be 
actively using the pwm polarity feature via a device tree (unlikely 
outside of embedded devices).

I think it'd still be a good idea to squash the errant warning so 
genuine errors are caught. I'll see if I can provoke the issue on 
devices I have access to. Are you in a position to try a patch if I come 
up with one?