linux-kernel - Re: [PATCH] Introduce support for Systems Management Driver over WMI for Dell Systems

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Date:   Mon, 14 Sep 2020 10:57:53 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Limonciello, Mario" <Mario.Limonciello@...l.com>,
        Divya Bharathi <divya27392@...il.com>,
        "dvhart@...radead.org" <dvhart@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "Bharathi, Divya" <Divya.Bharathi@...l.com>,
        "Ksr, Prasanth" <Prasanth.Ksr@...l.com>
Subject: Re: [PATCH] Introduce support for Systems Management Driver over WMI
 for Dell Systems

Hi,

On 9/14/20 10:45 AM, Hans de Goede wrote:

<snip>

>>>> +           lower_bound:    A file that can be read to obtain the lower
>>>> +           bound value of the <attr>
>>>> +
>>>> +           modifier:       A file that can be read to obtain attribute-level
>>>> +           dependency rule which has to be met to configure <attr>
>>>> +
>>>> +           scalar_increment:       A file that can be read to obtain the
>>>> +           resolution of the incremental value this attribute accepts.
>>>> +
>>>> +           upper_bound:    A file that can be read to obtain the upper
>>>> +           bound value of the <attr>
>>>
>>> Are these integers or also possibly floats? I guess possibly also floats, right?
>>> Then at a minimum this should specify which decimal-separator is used (I assume
>>> we will go with the usual '.' as decimal separator).
>>
>> In practice they're integers, but I don't see why they couldn't be floats.
> 
> Hmm, that is a bit hand-wavy, for an userspace ABI we really need to define
> this clearly. Either it is integers (which is fine), or it is floats and we need
> to define a decimal-separator as part of the ABI.
> 
> Note the reason why I started wondering about this in the first place is the
> scalar_increment attribute. I think that can use some clarification too.

p.s.

I just realized that the lower_ / upper_bound attributes would be
better if they were renamed to min_value and max_value then everyone
will immediately understand what they are without even needing to
consult the docs.

Regards,

Hans