On 11/22/2013 05:52 AM, Viresh Kumar wrote: > On 22 November 2013 18:07, Rafael J. Wysocki <r...@rjwysocki.net> wrote: >> On Friday, November 22, 2013 04:59:49 PM Viresh Kumar wrote: >>> Some platforms might want to change frequency before suspending governors. >>> Like: >>> - Some platform which want to set freq to max to speed up >>> suspend/hibernation >>> process. >>> - Some platform (like: Tegra or exynos), set this to min or bootloader's >>> frequency. >>> >>> This patch adds an option for those, so that they can specify this at call >>> to >>> ->init(), so that cpufreq core can take care of this before suspending >>> system. >>> >>> If this variable is not updated by ->init() then its value would be zero >>> and so >>> core wouldn't do anything. >>> >>> Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org> >> >> I don't think this is generally necessary, because the suspend/resume >> routines >> added by patch [1/2] will be executed very late during suspend or very early >> during resume and it shouldn't really matter what performance levels the CPUs >> are at then. > > There are few things here: > - I feel that the current place from where we have suspended stuff is not > gonna > fly. We are doing that in noirq and probably devices which might be required > during frequency transitions might already be down.. So we *may* need to > move that in dpm_suspend().. > - Secondly I want to understand why Tegra/Exynos has such code which I > mentioned above.. > > @Stephen, Kukjin and other samsung folks: Please provide some input here, > before your systems break in mainline :)
I believe we set the clock to a low value because fast clocks consume more power. Tegra architecturally supports a number of different suspend levels. Only some of those actually power off or gate the clock source itself. -- 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/
