On Friday 28 March 2014, Jean Delvare wrote: > Le Friday 28 March 2014 à 19:02 +0100, Arnd Bergmann a écrit : > > On Friday 28 March 2014, Jean Delvare wrote: > > > > > The current situation is kind of odd, because CPU_FREQ_CBE_PMI (bool) > > > depends on CPU_FREQ_CBE (tristate) so it is possible to have > > > CPU_FREQ_CBE=m and CPU_FREQ_CBE_PMI=y. If ppc_cbe_cpufreq_pmi really > > > depends on ppc_cbe_cpufreq, then that will fail, as ppc_cbe_cpufreq as > > > a module may not be loaded when ppc_cbe_cpufreq_pmi is initialized. The > > > compiler would complain about missing symbols. So I suspect this > > > dependency doesn't actually exist, otherwise after one year someone > > > would have noticed the build breakage, right? > > > > I believe CPU_FREQ_CBE can be built with support for CPU_FREQ_CBE_PMI > > or without, but if the PMI code is a module, then CPU_FREQ_CBE > > cannot be 'y'. > > > > > As a conclusion I believe the following changes should be applied: > > > * CPU_FREQ_CBE_PMI should be changed to a tristate. > > > * CPU_FREQ_CBE_PMI should not depend on CPU_FREQ_CBE. > > > > > > I can write and submit the patches once it is confirmed that this > > > changes are the right way to fix the problem. > > > > If you do this, you should also add > > > > depends on CPU_FREQ_CBE_PMI || !CPU_FREQ_CBE_PMI > > > > to the CPU_FREQ_CBE option, to correctly handle the dependency. > > Ah, my bad, I thought both modules were more or less independent, I > didn't realize ppc_cbe_cpufreq_pmi was actually a helper "module" for > ppc_cbe_cpufreq when enabled. > > Thinking about it some more, I think this would be much more simple to > build ppc_cbe_cpufreq_pmi.c as an object that would part of > ppc_cbe_cpufreq.ko. That is, build everything as a single module in the > end. That would solve the cross-dependency issue, and the code in > ppc_cbe_cpufreq_pmi would no longer have to be built-in. > > But well, I don't really have the time to look into this, especially as > I don't even have a powerpc machine at hand to test the changes. So if > nobody cares, things will have to stay the way they are. Fine with me. > > I don't actually see a problem with the current code, other than > > that CPU_FREQ_CBE_PMI could in theory be a module. This code is > > used only for an IBM machine that has been end-of-service for > > a couple of years. If anyone still wants to build kernels for > > it, they probably want it built-in anyway, and not have > > the same kernel run on other machines. > > Thanks for pointing this out. I don't know much about powerpc hardware > so I didn't realize that. We indeed ended up disabling this driver > altogether in our default ppc kernel config. Which was the easiest way > to solve our problem after all :-) You probably want to disable all of PPC_CELL anyway, which implies disabling this driver. There are a few hacks that get enabled if you want Cell support that have a small impact on performance on other platforms, and I don't expect anyone to run distro kernels on these machines any more. Arnd -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
