On Mon, Sep 9, 2013 at 3:13 PM, Nicolas Pitre nicolas.pitre@linaro.org wrote:
On Mon, 9 Sep 2013, Catalin Marinas wrote: Therefore having (equivalent of) MCPM in the firmware is _not_ cost effective. So it is to be expected that some people will make the engineering decision not to do the full power synchronization in the firmware and opt for simpler and more flexible alternatives to PSCI from the firmware perspective.
I'm sorry to bring this over again, but the discussion seems to keep being diverted away from this fundamental point with no concrete answers. I'm attributing this to a flaw in the overall secure world architecture that you have to put up with, hence the apparent diversion.
As strongly as I am able, I second this point. I hazard that for a lot of products, the secure world increases the complexity of the software stack without providing any benefit. This is particularly true for a lot of embedded products where all of the hardware support revolves around the Linux kernel. Putting part of the functionality in firmware adds complexity to debugging and it makes upgrades more complicated.
As Nico said, this is *not* an argument against PSCI. When secure world is there it is absolutely the right thing to do.
However, there needs to be acknowledgement that some users will chose to put as little as possible in Secure World because they don't need or want it.
g.