On Thu, Apr 25, 2013 at 12:08:02PM +0100, Stefano Stabellini wrote: > On Thu, 25 Apr 2013, Will Deacon wrote: > > On Thu, Apr 25, 2013 at 11:12:54AM +0100, Stefano Stabellini wrote: > > > However from the Linux POV these comments should regard the functions > > > exported by psci_operations, not the firmware interface, this is why I > > > think it makes sense to keep them in psci.h. > > > What we are saying is for example that psci_operations.cpu_on returns 0 > > > on success and < 0 on failure, and it takes a cpuid and an entry point > > > as parameters. We are not saying anything about the firmware interface. > > > > I disagree. You're explicitly stating that we pass the `cpuid of target CPU, > > as from MPIDR'. That's simply not true -- the firmware could choose any > > numbering scheme to identify the CPUs. For KVM and Xen, it *is* the mpidr, > > which is why psci-smp.c works at all, but that's where the comment belongs, > > not in this header file. > > I see, you want to keep psci_operations true to the firmware interface > while explaining that psci_smp makes some assumptions about it.
Precisely! :) > So the comment should be something like: > > /* > * psci_smp assumes that the following is true about PSCI: > * > * cpu_suspend Suspend the execution on a CPU > * @state we don't currently describe affinity levels, so just pass 0. > * @entry_point the first instruction to be executed on return > * returns 0 success, < 0 on failure > * > * cpu_off Power down a CPU > * @state we don't currently describe affinity levels, so just pass 0. > * no return on successful call > * > * cpu_on Power up a CPU > * @cpuid cpuid of target CPU, as from MPIDR > * @entry_point the first instruction to be executed on return > * returns 0 success, < 0 on failure > * > * migrate Migrate the context to a different CPU > * @cpuid cpuid of target CPU, as from MPIDR > * returns 0 success, < 0 on failure > * > */ That's certainly better, but I'd still rather see the comment with the implementation as there's a greater potential for confusion having it here. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
