On 3 Sep 2013, at 19:34, Christian Daudt csd@broadcom.com wrote:
On 13-09-03 11:11 AM, Dave Martin wrote:
From a personal point of view I would like to see wider use of MCPM, but ... it really comes down to how many native backends we get. If the way the TZ architecture works blocks native backends from existing on most platforms, we might see none or almost none, though.
I completely agree. I think that the the mcpm-on-psci scenario is (a) useful and (b) simple and (b) works on an already established kernel framework, so I see no reason to try to replace mcpm with psci for armv8, short or long term.
Sorry but I don't think you've followed the whole discussion. On ARMv8, you *need* calls to EL3 for CPU power management. With PSCI we try to standardise such calls. It's not about MCPM vs PSCI but about non-standard MCPM back-ends vs PSCI.
I have yet to see the value of MCPM on top of a PSCI back-end, other than allowing people to implement MCPM back-ends with non-standard EL3 calls (but happy to be proven wrong).
For cases where EL3 is not present (and PSCI not easily possible), I can accept MCPM but I would rather use it as a library driven from SoC-specific power code (e.g. under drivers/cpuidle/) rather than MCPM being the front-end to any CPU power management.
Catalin