On Thu, Dec 04, 2014 at 12:34:28PM +0100, Lucas Stach wrote: > Am Donnerstag, den 04.12.2014, 16:44 +0530 schrieb Viresh Kumar: > > + - voltage-tolerance: Specify the CPU voltage tolerance in percentage. > This is extremely ill defined. It doesn't say in which direction the > tolerance is to be applied. Can you go below or above the OPP specified > voltage? For now everyone just assumes that it has to work both ways. > Also with this binding the tolerance is applied for all OPPs, where is > very much depends on the individual OPP. Almost all specifications for voltages are done as either min/typ/max or +/- a target voltage. > If you are going to redefine OPPs anyway I would really like to see this > property die and rather have a min/max voltage per OPP. That way you can > properly express the OPP constraints. Most OPPs will likely allow a much > higher voltage than their minimal specified one, except when you go over > thermal limits with a high clock/voltage combination. If you've got a minimum and maximum you also need to specify a target, generally it's going to be better to go for the target voltage which may not be the midpoint and is unlikely to be one of the bounds. I do think it's sensible to have the option of doing both to more closely match datasheets. > > + - clock-latency: Specify the possible maximum transition latency for clock, > > + in unit of nanoseconds. > Why do we need this? This is property of the clock. We should be able to > handle this completely internally in the kernel. I don't know if the > clock API has something like this right now, but it should be a trivial > addition. Or have it be part of the clock binding at any rate.
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