Hi Nicolas, On Wed, Mar 28, 2012 at 03:17:29PM +0100, Nicolas Pitre wrote: > On Mon, 26 Mar 2012, Will Deacon wrote: > > > Now, if everything was device-tree based then we could simply use a > > different binding for each CPU but since we support perf on non-DT > > platforms, probing the CPU type is the best solution. I would like to avoid > > the probing code if we are initialised from DT, but I've not got round to it > > yet (this would be useful for big.LITTLE). > > Still... my opinion is that we should try to autodetect as much as > possible and avoid overstuffing the DT with content that can otherwise > be run-time probed. OK to use DT to override the probe for corner > cases, but IMHO the probe should be the default method of > initialization. The rational is that we want to spread knowledge about > part of the system and have it confined into respective drivers and > subsystems for easier maintenance. If the guy who has to maintain the > dts has to know all the details for everything then that won't scale and > the risk for discrepancies is increased. I agree that probing is preferable where possible but, since the PMUs are banked, we cannot reliably probe them on big.LITTLE platforms. I guess if there were some infrastructure for probing on the remote cluster, I could use that, but it seems like DT would be easier. Will
