Pavel Machek wrote: > On Mon 2006-09-11 17:36:33, Preece Scott-PREECE wrote: >>> From: Pavel Machek [mailto:pavel at ucw.cz] >>> >>>>>> - PowerOP is only one layer (towards the bottom) in a power >>>>>> management solution. >>>>>> - PowerOP does *not* replace cpufreq >>>>> PowerOP provides userland interface for changing processor >>> frequency. >>>>> That's bad -- duplicate interface. >>>> Basically the biggest problem with cpufreq interface is >>> that cpufreq >>>> has "chose predefined closest to a given frequency" functionality >>>> implemented in the kernel while there is _no_ any reason to >>> have this >>>> functionality implemented in the kernel if we have sysfs interface >>>> exported by PowerOP in place - you just >>> No, there is reason to keep that in kernel -- so that cpufreq >>> userspace interface can be kept, and so that resulting >>> kernel<->user interface is not ugly. >> --- >> >> Just as a data point, "keeping the cpufreq interface" is >> irrelevant to a number of us, because we configure it out >> of the system. I'm not really arguing that we should get >> rid of an existing kernel interface, but I don't see any >> reason why we shouldn't be able to have a separately >> configurable interface if cpufreq doesn't meet our needs. > > Configurable interfaces are evil, Are you saying that not having sysfs attribute nodes for entities which don't exist in a certain configuration is evil? In x86 configuration you'd like to have just one attribute - frequency? It's just subset of common case when all power parameters available on a platform are exported. In x86 configuration you'd like to echo arbitrary frequency value into 'sys/something' and have underneath logic to chose "closest" predefine frequency? No any reason to handle this in the kernel once frequency attribute is exported. > and I do not think you can push such > patch. You have developed your own little interface that suits your > needs -- and that's fine -- but now you are trying to push it into > mainline... and that is not, because those interfaces were not really > designed to work together. once cpufreq userland interface functionality which does not belong to the kernel is moved out of the kernel cpufreq interface becomes a subset of PowerOP sysfs interface. In other words this means that improvements of PM stack layers/interfaces design will allow to design/develop an universal userspace interface. We'd prefer to move gracefully in this direction though. Eugeny > Pavel
