Date: Wed, 23 Jun 2010 06:31:47 -0700
From: Guenter Roeck <guenter.roeck@ericsson.com>
To: Jean Delvare <khali@linux-fr.org>
CC: "lm-sensors@lm-sensors.org" <lm-sensors@lm-sensors.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [lm-sensors] Adding critical/fault limits to hwmon sysfs API
Message-ID: <20100623133147.GA19143@ericsson.com>
References: <20100620163759.GA7077@ericsson.com>
 <20100623144346.10acd898@hyperion.delvare>
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On Wed, Jun 23, 2010 at 08:43:46AM -0400, Jean Delvare wrote:
> Hi Guenter,
> 
> On Sun, 20 Jun 2010 09:37:59 -0700, Guenter Roeck wrote:
> > the current hwmon sysfs API does not specify critical or fault limits for voltage
> > and current readings.
> > 
> > Many recent power controller/monitoring chips have support for such limits in addition
> > to alarm limits. Typical action, when a the critical or fault limit is reached,
> > may be a board reset or power shutdown, or to report the fault condition.
> > 
> > Examples for chips supporting critical/fault limits are SMM665 and variants as well
> > as many PMBus devices, such as MAX8688, MAX16064, LTC2978, and others.
> > 
> > I think it would make sense to add critical/fault limits to the hwmon sysfs API,
> > to be able to report those limits if supported by a chip.
> > 
> > Any thoughts on this ?
> 
> I agree it would be good to have standard names (and libsensors
> support) if these features are popular. It might be a little difficult
> to come up with the right attribute names though.
> 
> For temperatures, we have temp[1-*]_crit, for the critical limit on the
> high end. We don't have a name for the critical limit on the low end,
> because no chip ever implemented that. The name we chose doesn't offer
> much possibilities for a nice name while staying consistent. Maybe
> "lcrit" would be acceptable for the low end critical limit, and we keep
> "crit" for the high end critical limit?
> 
How about {curr|in|temp}[1-*]_[min_]crit ?

In other words, keep _crit for the upper limit and introduce min_crit for the lower limit.
This would be a bit better aligned with the existing _min while maintaining _crit for the 
upper limit.

Guenter
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