Re: [PATCH 6/6 V4] hwmon: OMAP4: On die temperature sensor driver

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On Tue, Sep 6, 2011 at 11:42 PM, Guenter Roeck
<guenter.roeck@xxxxxxxxxxxx> wrote:
> On Tue, 2011-09-06 at 14:02 -0400, J, KEERTHY wrote:
>> On Thu, Sep 1, 2011 at 10:10 AM, Guenter Roeck
>> <guenter.roeck@xxxxxxxxxxxx> wrote:
>> > On Thu, Sep 01, 2011 at 12:09:14AM -0400, Paul Walmsley wrote:
>> >> On Wed, 31 Aug 2011, Guenter Roeck wrote:
>> >>
>> >> > On Wed, Aug 31, 2011 at 08:36:43PM -0400, Paul Walmsley wrote:
>> >> > > Hi
>> >> > >
>> >> > > Some comments.
>> >> > >
>> >> > > On Wed, 31 Aug 2011, Keerthy wrote:
>> >> > >
>> >> > [ ... ]
>> >> > >
>> >> > > > +}
>> >> > > > +
>> >> > > > +/* Sysfs hook functions */
>> >> > >
>> >> > > These should be conditionally compiled out if sysfs isn't compiled in.
>> >> > >
>> >> > The whole point of the hwmon subsystem is to expose hardware monitoring information
>> >> > to userland using sysfs. hwmon without sysfs doesn't make sense.
>> >> >
>> >> > So, if anything, it might make sense to disable the entire hwmon tree if sysfs is disabled.
>> >> > But please no conditionals in the code.
>> >>
>> >> Hmm.  This IP block is more than just a sensor.  It also can interrupt the
>> >> CPU and/or trigger a GPIO line (to shut down the chip) if the chip
>> >> temperature crosses some thresholds.  On some OMAPs, the thresholds are
>> >> fixed; on others, they are software-programmable.  That functionality
>> >> shouldn't require sysfs; it's almost closer to an x86 MCE.
>> >>
>> >> So based on your comments, it sounds like we should move that part of the
>> >> code to a different driver, and just leave the basic software thermal
>> >> monitoring here?
>> >>
>> > Good point. This definitely requires some thought. hwmon is meant to be hw monitoring,
>> > as the name says, not thermal management. Maybe this entire driver should be a thermal driver
>> > instead ?
>>
>> This driver is not taking any action on THSUT. This is not doing the thermal
>> management. It is a driver exposing configurable temperature thresholds.
>
> What sense would it make, then, to keep the driver around even if SYSFS
> is not defined ?

SYSFS nodes are defined for t_hot and t_cold thresholds. SYSFS nodes
are not defined
for TSHUT thresholds which are different.

>
> Note that I am not looking at the code right now, but at the suggestion
> that the driver would do something useful if SYSFS is not defined.
> Question is what that is, and if that part of it should reside in a
> hwmon driver.
>
> Thanks,
> Guenter
>
>
>



-- 
Regards and Thanks,
Keerthy
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