On Thu, 2010-12-09 at 16:26 -0500, Ira W. Snyder wrote: > On Thu, Dec 09, 2010 at 08:58:58AM -0800, Guenter Roeck wrote: > > Hi all, > > > > I am looking through libsensors and the hwmon sysfs ABI to identify and fix > > inconsistencies. > > > > One problem I noticed is powerX_alarm, which is defined as "system is drawing > > more power than the cap allows". > > > > powerX_cap is defined as " ... The *_cap files only appear if the cap is known > > to be enforced by hardware". > > > > Now there are conditions where power limits are defined and supported, > > but the hardware does not enforce it. Similar, there are devices reporting power > > alarms not associated with cap enforcement. Examples are ltc4215 and PMBus devices. > > powerX_alarm is supported by the ltc4215 driver, but there is no _cap attribute, > > and the alarm is not associated with a maximum, thus a reported alarm doesn't > > really reflect the ABI. > > > > In the ltc4215, the power1_alarm occurs when the output voltage of the > chip is outside a certain range. This range is specified by external > resistors, specific to each application. They are not required to be a > specific value by the hardware. > > I guess that the ltc4215 driver's use of powerX_alarm doesn't follow the > ABI document. > > In essence, the power1_alarm is connected to the chip's power good > output (negated). Should the ABI have a powerX_good or powerX_fail > attribute? > I think powerX_alarm pretty well covers it. My concern is with the ABI description/definition, which is not in line with other _alarm attributes. Question for the ltc4215 driver, though, is if power1_alarm is appropriate in the first place. After reading the datasheet, I noticed that it does not really report a power problem, but "output voltage low". So I wonder it the attribute in the driver should be "in2_alarm" or possibly "in2_min_alarm" instead of power1_alarm, and if the power attributes should be dropped entirely. We could possibly add an inX_fail alarm attribute to cover the condition reported by the ltc4215. Not sure if that would be worth it, but it might be worth a thought. Thanks, Guenter _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
