On 07/08/13 17:17, Mark Rutland wrote: > On Tue, Aug 06, 2013 at 02:45:34PM +0100, Nishanth Menon wrote: >> On 14:15-20130802, Mark Rutland wrote: >>> On Thu, Aug 01, 2013 at 05:25:06PM +0100, Nishanth Menon wrote: >>>> On 08/01/2013 08:54 AM, Mark Rutland wrote: >>>>> On Wed, Jul 31, 2013 at 05:27:39PM +0100, Nishanth Menon wrote: >>>>>> On 07/31/2013 11:11 AM, Mark Rutland wrote: >>>>>>> On Wed, Jul 31, 2013 at 04:58:22PM +0100, Nishanth Menon wrote: >>>>>>>> On 07/31/2013 10:29 AM, Mark Rutland wrote: >>>>>>>>> On Wed, Jul 31, 2013 at 03:46:34PM +0100, Nishanth Menon wrote: >>>>>>>>>> On 07/31/2013 06:14 AM, Sudeep KarkadaNagesha wrote: >>>>>>>>>>> On 30/07/13 21:48, Nishanth Menon wrote: >>>>>>>>>>>> On 07/30/2013 01:34 PM, Stephen Warren wrote: >>>>>>>>>>>>> On 07/30/2013 12:00 PM, Sudeep KarkadaNagesha wrote: >> [...] >>>> >>>>> >>>>> * Performance profiles, in which you have a set of OPP tables for >>>>> "performance, "low-power", and whatever else. This arbitrary split >>>>> seems like a configuration decision rather than a hardware description >>>>> unless there is some hard limit that cannot be detected (e.g. the >>>>> processor can function at some arbitrary high speed, but becomes hot >>>>> enough to melt something, and there's no temperature sensor to handle >>>>> this case dynamically). >>>> >>>> precisely -> I think I point this out in this thread: >>>> http://marc.info/?l=devicetree&m=137535932402560&w=2 >>> >>> The one thing I don't like is the arbitrary grouping into profiles, as >>> the division is entirely a configuration decision. The operating points >>> themselves are a hardware capability, and it may make sense to describe >>> the feasible points for a device in the dt, but I don't want to have >>> different profiles exported because it straddles the line of the dt >>> telling us how to use the hardware rather than what the hardware is, and >>> will come back to bite us later if we want to handle cpu frequency >>> decisions differently. >> >> I can understand why it seems to wrongly indicate *how* to use the >> hardware, rather than *what the hardware is* - Lets try it this way: >> - if Bit X is set in efuse, one cannot use high performance mode >> - If PDN (Power Distribution Network) guidelines are not met, one cannot >> use high performance mode. >> >> These constrain *hardware capability* you can do on that SoC+Board >> combination - that is exactly what we have been struggling to describe >> here. These are not *how to use hardware* profiles, but *hardware >> capability* profiles whose selection is upto to the System in >> discussion - example - SoC x will decide on bit based decision and >> forbid Board file overrides while an SoC y family might choose another >> path.. Framework and dts should not dictate policy and we dont try to >> do that here. >> >> How to use the hardware within the *capability costraints* is upto >> drivers, there is no attempt to define that in my proposal. > > I'm happy to have the OPPs, as your arguments certainly make sense. My > only concern is that if we have them grouped in some fashion in dt (e.g. > profiles), people will use this as configuration, treating the groups of > OPPs differnetly (prefering a 'performance' or 'low-power' profile). I'd > prefer that any decision on how to use the provided OPP values were done > in the kernel dynamically. > > I suspect even if we remove profile names, people will attempt to read > some semantics into the groupings. For that reason, I'd prefer to have a > single OPP table for any device (though this table could be shared by > devices). > Until we get more feedback and agreement on new proposal can we have this simple amendment in this patch to the existing binding ? Since the new proposal[1] is backward compatible(this patch adding support for option#5 to existing option#1), we will have to add support for other binding options in [1] later. This is needed to support shared OPPs with simple/single OPP profile and also to fix the broken and unused binding @Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt Regards, Sudeep [1] http://www.spinics.net/lists/cpufreq/msg06563.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
