Hi Krzysztof, Please see my comment below.
On 16.07.2014 10:23, Krzysztof Kozlowski wrote: > On Exynos4 USE_DELAYED_RESET_ASSERTION must be set in > ARM_COREx_OPTION register during CPU power down. This is the proper way > of powering down CPU on Exynos4. > > Additionally on Exynos4212 without this the CPU clock down feature won't > work after powering down some CPU and the online CPUs will work at full > frequency chosen by CPUfreq governor. > > Signed-off-by: Krzysztof Kozlowski <[email protected]> [snip] > @@ -36,6 +36,14 @@ static inline void cpu_leave_lowpower(void) > : "=&r" (v) > : "Ir" (CR_C), "Ir" (0x40) > : "cc"); > + > + if (soc_is_exynos4()) { > + unsigned int tmp; > + > + tmp = __raw_readl(EXYNOS_ARM_CORE_OPTION(core_id)); > + tmp &= ~(S5P_USE_DELAYED_RESET_ASSERTION); > + __raw_writel(tmp, EXYNOS_ARM_CORE_OPTION(core_id)); > + } This code is executed only if the CPU doesn't manage to power off before already receiving a wake-up event. Otherwise the context is lost after wfi(), as the core power is being cut down. The normal wake-up path goes through platsmp's exynos_boot_secondary() and I believe that setting of S5P_USE_DELAYED_RESET_ASSERTION should be taken care there as well. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
