Re: [lm-sensors] Need some guidance on adhering to the sysfs

[Hans de Goede <j.w.r.degoede@hhs.nl>]

Juerg Haefliger wrote:
> On 4/22/07, Juerg Haefliger <juergh@gmail.com> wrote:
>> On 4/22/07, Hans de Goede <j.w.r.degoede@hhs.nl> wrote:
>> > Juerg Haefliger wrote:
>> > > On 4/22/07, Hans de Goede <j.w.r.degoede@hhs.nl> wrote:
>> > >> Juerg Haefliger wrote:
>> > >>> Hi Jean,
>> > >>>
>> > >>> On 4/22/07, Jean Delvare <khali@linux-fr.org> wrote:
>> > >>>> Hi Juerg,
>> > >>>>
>> > >>>> On Thu, 19 Apr 2007 12:04:28 -0700, Juerg Haefliger wrote:
>> > >>>>> George, Jean,
>> > >>>>>
>> > >>>>> I'm struggling with the same issue for the DME1737 I'm currently
>> > >>>>> working on. This chip also features temp zones and "hottest of 
>> x,y,z"
>> > >>>>> PWM control. The current sysfs standard is not flexible enough to
>> > >>>>> handle these features, especially the combination of a single PWM
>> > >>>>> being controlled by multiple temp inputs and multiple PMWs being
>> > >>>>> controlled by the same temp input. I believe we need another 
>> layer of
>> > >>>>> mapping. I.e. temp->pwm is not sufficient, but rather 
>> temp->zone->pwm.
>> > >>>>>
>> > >>>>> I therefore propose the add the following sysfs attributes to 
>> our standard:
>> > >>>>>
>> > >>>>> zone[1-*]_auto_channels_temp   for temp-to-zone mapping
>> > >>>>> pwm[1-*]_auto_channels_zone   for zone-to-pwm mapping
>> > >>>>> zone[1-*]_auto_point[1-*]_temp   for zone temp auto points.
>> > >>>> I don't see what value it adds compared to what we currently have.
>> > >>>>
>> > >>>> We have pwm[1-*]_auto_channels_temp, which is a bit vector. We 
>> have one
>> > >>>> file per PWM, one bit per temperature channel, so all in all we 
>> have a
>> > >>>> Npwm x Ntemp matrix, or N-N relation between PWM and 
>> temperatures. This
>> > >>>> already allows us to handle cases such as "the hottest of tempA 
>> and
>> > >>>> tempB control pwmC" or "tempD controls pwmE and pwmF".
>> > >>> Yes, I understand that.
>> > >>>
>> > >>>
>> > >>>> You propose to add the concept of zone. According to the above, 
>> each
>> > >>>> zone could include any temperature channel, so we have a N-N 
>> relation
>> > >>>> between zones and temperatures. Then you express another N-N 
>> relation
>> > >>>> between PWM channels and zones. As far as I can see, this 
>> results in a
>> > >>>> N-N relation between temperatures and PWM, just expressed 
>> differently.
>> > >>>> Am I missing something? What do you think it would let us express,
>> > >>>> which the current model doesn't?
>> > >>> What I can't seem to map to our current standard (or maybe I just
>> > >>> don't see it) is the concept of multiple sets of thermal thresholds
>> > >>> for a single temp input. Example: pwm2 is controlled by zone2 
>> and pwm3
>> > >>> is controlled by zone3 but both zone2 and zone3 are controlled by
>> > >>> temp3. Both zone2 & 3 have different thermal thresholds.
>> > >>>
>> > >>> With the current standard I can only apply one set of thresholds to
>> > >>> temp3 via temp3_auto_point[1-*]_temp.
>> > >>>
>> > >> Thats easy, AFAIK you can have either 
>> temp[1-*]_auto_point[1-*]_temp,
>> > >> or pwm[1-*]_auto_point[1-*]_temp, iow you can couple the autopoints
>> > >> to either a temp channel or a pwm channel depending on if the
>> > >> thresholds are set per temp channel or per pwm channel.
>> > >
>> > > That's not going to work. I can't use temp[1-*]_auto_point[1-*]_temp
>> > > because there are multiple sets of thresholds for a single temp input
>> > > and I can't use pwm[1-*]_auto_point[1-*]_temp either because then the
>> > > "hottest of x,y,z" doesn't work.
>> > >
>> >
>> > Can't you use pwm[1-*]_auto_channels_temp for that?
>>
>> Yes, I do. OK, I wasn't clear enough in my previous post. The problem
>> is the thermal thresholds. How would you implement the following
>> example with the current sysfs standard?
>>
>> temp3 maps to zone2
>> temp3 maps to zone3
>> zone2 has min and max temp thresholds
>> zone3 has min and max temp thresholds
>> pwm2 is controlled by zone2
>> pwm3 is controlled by hottest of zone2 or zone3
>>
>> See what the problem is? There are 2 sets of thermal thresholds for
>> pwm3 and 2 sets for temp3.
> 
> OK just realized that this is a silly example :-) Let's try again:
> 
> temp1 maps to zone1
> temp3 maps to zone2
> temp3 maps to zone3
> zone1 has min and max temp thresholds
> zone2 has min and max temp thresholds
> zone3 has min and max temp thresholds
> pwm1 is controlled by zone1
> pwm2 is controlled by zone2
> pwm3 is controlled by hottest of zone1 or zone3
> 
> Not sure if that makes more sense but the DME1737 can certainly be
> programmed that way...
> 

I see your ppoint, and I don't know how to handle that with the current scheme,

Regards,

Hans


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