lkml.org 
[lkml]   [2013]   [Jul]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [lm-sensors] [RESEND PATCH V1 0/9] thermal: introduce DT thermal zone build
    On 07/18/2013 03:21 PM, Guenter Roeck wrote:
    > On Thu, Jul 18, 2013 at 11:18:05AM -0600, Stephen Warren wrote:
    >> On 07/18/2013 07:53 AM, Eduardo Valentin wrote:
    >>> Hello Guenter,
    >>>
    >>> On 17-07-2013 18:09, Guenter Roeck wrote:
    >>>> On Wed, Jul 17, 2013 at 11:17:19AM -0400, Eduardo Valentin
    >>>> wrote:
    >>>>> Hello all,
    >>>>>
    >>>>> As you noticed, I am working in a way to represent thermal
    >>>>> data using device tree [1]. Essentially, this should be a way
    >>>>> to say what to do with a sensor and how to associate (cooling)
    >>>>> actions with it.
    >>>>>
    >>>> Seems to me that goes way beyond the supposed scope of devicetree
    >>>> data. Devicetree data is supposed to describe hardware, not its
    >>>> configuration or use. This is clearly a use case.
    >>>
    >>> Thanks for rising your voice here. It is important to know what
    >>> hwmon ppl think about this.
    >>
    >> I meant to find time to read Guenter's original email where he
    >> initially objected to putting data into DT, and determine exactly what
    >> was being objected to. I still haven't:-( However, the arguments that
    >> Eduardo stated in his email do make sense to me; I agree that
    >> temperature limits really are a description of HW. Details of which
    >> cooling methods to invoke when certain temperature limits are reached
    >> is also part of the HW/system design, and hence I would tend to agree
    >> that they're appropriate to include in DT. Anyway, that's just my 2
    >> cents on the matter:-)
    >
    > Many systems have multiple profiles for various use cases (high performance,
    > low power etc), and limits are different based on the use case. If that means
    > you are going to have multiple devicetree variants based on the profile,
    > I would argue that you crossed the line.

    Yes, I can see that argument. However, a counter-point:

    * I believe we do need a DT binding to describe the absolute thermal
    limits of a system, for safety/correctness of system operation.

    * We need to define a syntax/schema to represent that.

    * If we then want to implement additional profiles with stricter limits,
    do we really want to invent a different syntax/schema to represent
    those? Representing them in the same way seems like good use of the
    design, mind-share, etc.

    * Perhaps that doesn't mean that the additional profiles have to be in
    DT though; just that we somehow make any other representation of those
    profiles as close to the DT representation in syntax/structure as we
    can, to get maximum re-use.

    > With thermal profiles it gets even more
    > complicated, as those parameters may be played around with and changed
    > multiple times to find the best settings to achieve optimal cooling.

    To me, that sounds more like fixing a bug in the initial data, rather
    than something which fundamentally affects how the data should be
    represented.

    > Does this describe hardware ? I don't think so, but, as I mentioned before,
    > maybe I am wrong.



    \
     
     \ /
      Last update: 2013-07-19 22:01    [W:4.488 / U:0.184 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site