Messages in this thread | | | Date | Mon, 17 Nov 2014 13:51:42 +0100 | From | Lukasz Majewski <> | Subject | Re: [PATCH 5/8] thermal:cpu cooling:tegra: Provide deferred probing for tegra driver |
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Hi Thierry,
> On Fri, Nov 14, 2014 at 12:24:37PM +0100, Lukasz Majewski wrote: > > Hi Mikko, > > > > > Tested-by: Mikko Perttunen <mikko.perttunen@kapsi.fi> > > > > Thanks for testing. > > > > > > > > One potential issue I can see is that if the cpufreq driver fails > > > to probe then you'll never get the thermal driver either. For > > > example, Tegra124 currently has no cpufreq driver, so if > > > CONFIG_CPU_THERMAL was enabled, then the soctherm driver would > > > never be able to probe. > > > > Yes, this is a potential issue. However, this option in > > tegra_defconfig is by default disabled when thermal is enabled. > > Not everybody uses tegra_defconfig for their kernel builds. In fact > I'd imagine that the majority of kernels use a variant of > multi_v7_defconfig and therefore CPU_THERMAL might get enabled > irrespective of any Tegra support.
I see your point.
> > I think a better solution would be to add this check only when proper > support for CPU frequency based cooling is added. That is, when a call > to cpufreq_cooling_register() (or a variant thereof) is added.
For the above reason the code is only compiled in when user enable CONFIG_CPU_THERMAL.
> > But while at it, why not make it so that cpufreq_cooling_register() > detects if a cpufreq driver has been registered yet and propagate > -EPROBE_DEFER if necessary?
cpufreq_cooling_register() may be a good place to add check for deferred probe.
The problem with cpufreq_cooling_register() is that it may be called late in the probe function (as it is done now in Exynos).
> > Thierry
-- Best regards,
Lukasz Majewski
Samsung R&D Institute Poland (SRPOL) | Linux Platform Group
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