Russell King - ARM Linux wrote: > > > > Hi Russell and all, > > > > I'd like to share requirement of EXYNOS4210 PM. > > > > Now if there is wakeup source which is pending before entering suspend mode, > > PMU(Power Management Unit) handles WFI instruction as NOP on EXYNOS4210. > But > > it seems that current cpu_suspend() cannot support this. So how can/should > > we handle this case? > > See patch from June 13th posted to the hibernate thread. This allows > the finisher function to return, though it should only return if it is > certain that the system will not enter suspend. > > Is this true of the current exynos4 code? It seems that the current > code will panic() if the WFI is executed as a NOP. > Yes, you're right, current code cannot control it. Supporting this case will be scheduled in next patch. > > And this is another case. For example, assume that ARM is power down mode > > and outer cache(L2 cache) data is retention state to use L2 cache data after > > wakeup. In this case, according to wakeup sequence, firstly L1 cache is > > enabled in cpu_resume() then L2 cache will be enabled which is implemented > > in Samsung SoC specific code. So how can be handled the coherency problem > > between L1 cache and L2 cache? > > You could ensure that L2 is ready to be re-enabled before calling > cpu_resume. As the C bit in the control register will be cleared, > L2 should not be used at that point, until after the MMU is re- > initialized. Russell, thanks for your kindly explanation :) Best regards, Kgene. -- Kukjin Kim <kgene.kim@xxxxxxxxxxx>, Senior Engineer, SW Solution Development Team, Samsung Electronics Co., Ltd. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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