Mark Brown wrote: > On Tue, Aug 17, 2010 at 11:06:10AM -0700, Bobby Crabtree wrote: >> I'm looking to upstream a new feature in which the regulator core >> aggregates voltage requests from multiple consumers and applies the best >> fitting voltage (e.g. max voltage) to a shared supply. The core would > > It's unlikely that the highest voltage would ever be the best choice... > We do need the highest voltage. Let's say we have two consumers (A and B). Both require 1.3V for "normal" operations. Then let's say that consumer A can save power by reducing the voltage to 1.1V (but it doesn't require 1.1V). If the core were to immediately apply 1.1V, then the 1.3V requirement of consumer B would not be satisfied. >> recompute the best fitting voltage when a consumer requests a voltage >> change or requests to enable/disable the regulator (similar logic to >> DRMS). > >> The reason we need this feature is for power savings. It would allow two >> or more consumers to "vote" on a voltage that's lower than the normal >> operating voltage. > > This was actually a feature of the regulator API when originally > proposed, it got dropped for ease of review but there's some remanants > of this in the code so it shouldn't be hard to resurrect. Whenever a > voltage was set the code stored the range on the consumer then iterated > over all consumers applying their ranges plus the machine constraints > rather than just using the immediate value. > I noticed some of the remnants. But I'm not sure I follow what you are saying. What range would the core actually propagate to the driver? The minimum min_uV and the maximum max_uV? We need the core to propagate the maximum min_uV and the maximum max_uV. >> 1. Introduce a new API: > >> int regulator_set_optimum_voltage(struct regulator *regulator, >> int min_uV, int max_uV); > > Why would you want to do this? This is just the same arguments as the > standard regulator_set_voltage() call and if we're ever setting anything > other than the optimal voltage we probably ought to just stop doing > that. > "Optimum" was a bad choice of words. Seems that a new API isn't preferred, so let's scrap this option. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
