[PATCH] ARM: test for PMU feature on v7 (v2 with typo fix)

[Nicolas Pitre]

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.


Nicolas