Re: several messages
Hi Nicolas, On Fri, Jul 4, 2014 at 9:43 AM, Nicolas Pitre nicolas.pi...@linaro.org wrote: On Fri, 4 Jul 2014, Abhilash Kesavan wrote: Hi Nicolas, On Fri, Jul 4, 2014 at 12:30 AM, Nicolas Pitre nicolas.pi...@linaro.org wrote: On Thu, 3 Jul 2014, Abhilash Kesavan wrote: Hi Nicolas, On Thu, Jul 3, 2014 at 9:15 PM, Nicolas Pitre nicolas.pi...@linaro.org wrote: On Thu, 3 Jul 2014, Abhilash Kesavan wrote: On Thu, Jul 3, 2014 at 6:59 PM, Nicolas Pitre nicolas.pi...@linaro.org wrote: Please, let's avoid going that route. There is no such special handling needed if the API is sufficient. And the provided API allows you to suspend a CPU or shut it down. It shouldn't matter at that level if this is due to a cluster switch or a hotplug event. Do you really need something else? No, just one local flag for suspend should be enough for me. Will remove these. [...] Changes in v5: - Removed the MCPM flags and just used a local flag to indicate that we are suspending. [...] -static void exynos_power_down(void) +static void exynos_mcpm_power_down(u64 residency) { unsigned int mpidr, cpu, cluster; bool last_man = false, skip_wfi = false; @@ -150,7 +153,12 @@ static void exynos_power_down(void) BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP); cpu_use_count[cpu][cluster]--; if (cpu_use_count[cpu][cluster] == 0) { - exynos_cpu_power_down(cpunr); + /* + * Bypass power down for CPU0 during suspend. This is being + * taken care by the SYS_PWR_CFG bit in CORE0_SYS_PWR_REG. + */ + if ((cpunr != 0) || (residency != S5P_CHECK_SLEEP)) + exynos_cpu_power_down(cpunr); if (exynos_cluster_unused(cluster)) { exynos_cluster_power_down(cluster); @@ -209,6 +217,11 @@ static void exynos_power_down(void) /* Not dead at this point? Let our caller cope. */ } +static void exynos_power_down(void) +{ + exynos_mcpm_power_down(0); +} [...] +static int notrace exynos_mcpm_cpu_suspend(unsigned long arg) +{ + /* MCPM works with HW CPU identifiers */ + unsigned int mpidr = read_cpuid_mpidr(); + unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + + __raw_writel(0x0, sysram_base_addr + EXYNOS5420_CPU_STATE); + + mcpm_set_entry_vector(cpu, cluster, exynos_cpu_resume); + + /* + * Pass S5P_CHECK_SLEEP flag to the MCPM back-end to indicate that + * we are suspending the system and need to skip CPU0 power down. + */ + mcpm_cpu_suspend(S5P_CHECK_SLEEP); NAK. When I say local flag with local meaning, I don't want you to smuggle that flag through a public interface either. I find it rather inelegant to have the notion of special handling for CPU0 being spread around like that. If CPU0 is special, then it should be dealth with in one place only, ideally in the MCPM backend, so the rest of the kernel doesn't have to care. Again, here's what I mean: static void exynos_mcpm_down_handler(int flags) { [...] if ((cpunr != 0) || !(flags SKIP_CPU_POWERDOWN_IF_CPU0)) exynos_cpu_power_down(cpunr); [...] } static void exynos_mcpm_power_down() { exynos_mcpm_down_handler(0); } static void exynos_mcpm_suspend(u64 residency) { /* * Theresidency argument is ignored for now. * However, in the CPU suspend case, we bypass power down for * CPU0 as this is being taken care by the SYS_PWR_CFG bit in * CORE0_SYS_PWR_REG. */ exynos_mcpm_down_handler(SKIP_CPU_POWERDOWN_IF_CPU0); } And SKIP_CPU_POWERDOWN_IF_CPU0 is defined in and visible to mcpm-exynos.c only. Sorry if I am being dense, but the exynos_mcpm_suspend function would get called from both the bL cpuidle driver as well the exynos pm code. What is that exynos pm code actually doing? exynos pm code is shared across Exynos4 and 5 SoCs. It primarily does a series of register configurations which are required to put the system to sleep (some parts of these are SoC specific and others common). It also populates the suspend_ops for exynos. In the current patch, exynos_suspend_enter() is where I have plugged in the mcpm_cpu_suspend call. This patch is based on the S2R series for 5420 (http://comments.gmane.org/gmane.linux.kernel.samsung-soc/33898), you may also have a look at that for a clearer picture. We want to skip CPU0 only in case of the S2R case i.e. the pm code and keep the CPU0 power down code for all other cases including CPUIdle. OK. If so
Re: several messages
On Thu, 3 Jul 2014, Abhilash Kesavan wrote: Hi Nicolas, On Thu, Jul 3, 2014 at 9:15 PM, Nicolas Pitre nicolas.pi...@linaro.org wrote: On Thu, 3 Jul 2014, Abhilash Kesavan wrote: On Thu, Jul 3, 2014 at 6:59 PM, Nicolas Pitre nicolas.pi...@linaro.org wrote: Please, let's avoid going that route. There is no such special handling needed if the API is sufficient. And the provided API allows you to suspend a CPU or shut it down. It shouldn't matter at that level if this is due to a cluster switch or a hotplug event. Do you really need something else? No, just one local flag for suspend should be enough for me. Will remove these. [...] Changes in v5: - Removed the MCPM flags and just used a local flag to indicate that we are suspending. [...] -static void exynos_power_down(void) +static void exynos_mcpm_power_down(u64 residency) { unsigned int mpidr, cpu, cluster; bool last_man = false, skip_wfi = false; @@ -150,7 +153,12 @@ static void exynos_power_down(void) BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP); cpu_use_count[cpu][cluster]--; if (cpu_use_count[cpu][cluster] == 0) { - exynos_cpu_power_down(cpunr); + /* + * Bypass power down for CPU0 during suspend. This is being + * taken care by the SYS_PWR_CFG bit in CORE0_SYS_PWR_REG. + */ + if ((cpunr != 0) || (residency != S5P_CHECK_SLEEP)) + exynos_cpu_power_down(cpunr); if (exynos_cluster_unused(cluster)) { exynos_cluster_power_down(cluster); @@ -209,6 +217,11 @@ static void exynos_power_down(void) /* Not dead at this point? Let our caller cope. */ } +static void exynos_power_down(void) +{ + exynos_mcpm_power_down(0); +} [...] +static int notrace exynos_mcpm_cpu_suspend(unsigned long arg) +{ + /* MCPM works with HW CPU identifiers */ + unsigned int mpidr = read_cpuid_mpidr(); + unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + + __raw_writel(0x0, sysram_base_addr + EXYNOS5420_CPU_STATE); + + mcpm_set_entry_vector(cpu, cluster, exynos_cpu_resume); + + /* + * Pass S5P_CHECK_SLEEP flag to the MCPM back-end to indicate that + * we are suspending the system and need to skip CPU0 power down. + */ + mcpm_cpu_suspend(S5P_CHECK_SLEEP); NAK. When I say local flag with local meaning, I don't want you to smuggle that flag through a public interface either. I find it rather inelegant to have the notion of special handling for CPU0 being spread around like that. If CPU0 is special, then it should be dealth with in one place only, ideally in the MCPM backend, so the rest of the kernel doesn't have to care. Again, here's what I mean: static void exynos_mcpm_down_handler(int flags) { [...] if ((cpunr != 0) || !(flags SKIP_CPU_POWERDOWN_IF_CPU0)) exynos_cpu_power_down(cpunr); [...] } static void exynos_mcpm_power_down() { exynos_mcpm_down_handler(0); } static void exynos_mcpm_suspend(u64 residency) { /* * Theresidency argument is ignored for now. * However, in the CPU suspend case, we bypass power down for * CPU0 as this is being taken care by the SYS_PWR_CFG bit in * CORE0_SYS_PWR_REG. */ exynos_mcpm_down_handler(SKIP_CPU_POWERDOWN_IF_CPU0); } And SKIP_CPU_POWERDOWN_IF_CPU0 is defined in and visible to mcpm-exynos.c only. Sorry if I am being dense, but the exynos_mcpm_suspend function would get called from both the bL cpuidle driver as well the exynos pm code. What is that exynos pm code actually doing? We want to skip CPU0 only in case of the S2R case i.e. the pm code and keep the CPU0 power down code for all other cases including CPUIdle. OK. If so I missed that somehow (hint hint). If I call exynos_mcpm_down_handler with the flag in exynos_mcpm_suspend(), CPUIdle will also skip CPU0 isn't it ? As it is, yes. You could logically use an infinite residency time (something like U64_MAX) to distinguish S2RAM from other types of suspend. Yet, why is this SYS_PWR_CFG bit set outside of MCPM? Couldn't the MCPM backend handle it directly instead of expecting some other entity to do it? Nicolas -- To unsubscribe from this list: send the line unsubscribe linux-samsung-soc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: several messages
On Fri, 4 Jul 2014, Abhilash Kesavan wrote: Hi Nicolas, On Fri, Jul 4, 2014 at 12:30 AM, Nicolas Pitre nicolas.pi...@linaro.org wrote: On Thu, 3 Jul 2014, Abhilash Kesavan wrote: Hi Nicolas, On Thu, Jul 3, 2014 at 9:15 PM, Nicolas Pitre nicolas.pi...@linaro.org wrote: On Thu, 3 Jul 2014, Abhilash Kesavan wrote: On Thu, Jul 3, 2014 at 6:59 PM, Nicolas Pitre nicolas.pi...@linaro.org wrote: Please, let's avoid going that route. There is no such special handling needed if the API is sufficient. And the provided API allows you to suspend a CPU or shut it down. It shouldn't matter at that level if this is due to a cluster switch or a hotplug event. Do you really need something else? No, just one local flag for suspend should be enough for me. Will remove these. [...] Changes in v5: - Removed the MCPM flags and just used a local flag to indicate that we are suspending. [...] -static void exynos_power_down(void) +static void exynos_mcpm_power_down(u64 residency) { unsigned int mpidr, cpu, cluster; bool last_man = false, skip_wfi = false; @@ -150,7 +153,12 @@ static void exynos_power_down(void) BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP); cpu_use_count[cpu][cluster]--; if (cpu_use_count[cpu][cluster] == 0) { - exynos_cpu_power_down(cpunr); + /* + * Bypass power down for CPU0 during suspend. This is being + * taken care by the SYS_PWR_CFG bit in CORE0_SYS_PWR_REG. + */ + if ((cpunr != 0) || (residency != S5P_CHECK_SLEEP)) + exynos_cpu_power_down(cpunr); if (exynos_cluster_unused(cluster)) { exynos_cluster_power_down(cluster); @@ -209,6 +217,11 @@ static void exynos_power_down(void) /* Not dead at this point? Let our caller cope. */ } +static void exynos_power_down(void) +{ + exynos_mcpm_power_down(0); +} [...] +static int notrace exynos_mcpm_cpu_suspend(unsigned long arg) +{ + /* MCPM works with HW CPU identifiers */ + unsigned int mpidr = read_cpuid_mpidr(); + unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + + __raw_writel(0x0, sysram_base_addr + EXYNOS5420_CPU_STATE); + + mcpm_set_entry_vector(cpu, cluster, exynos_cpu_resume); + + /* + * Pass S5P_CHECK_SLEEP flag to the MCPM back-end to indicate that + * we are suspending the system and need to skip CPU0 power down. + */ + mcpm_cpu_suspend(S5P_CHECK_SLEEP); NAK. When I say local flag with local meaning, I don't want you to smuggle that flag through a public interface either. I find it rather inelegant to have the notion of special handling for CPU0 being spread around like that. If CPU0 is special, then it should be dealth with in one place only, ideally in the MCPM backend, so the rest of the kernel doesn't have to care. Again, here's what I mean: static void exynos_mcpm_down_handler(int flags) { [...] if ((cpunr != 0) || !(flags SKIP_CPU_POWERDOWN_IF_CPU0)) exynos_cpu_power_down(cpunr); [...] } static void exynos_mcpm_power_down() { exynos_mcpm_down_handler(0); } static void exynos_mcpm_suspend(u64 residency) { /* * Theresidency argument is ignored for now. * However, in the CPU suspend case, we bypass power down for * CPU0 as this is being taken care by the SYS_PWR_CFG bit in * CORE0_SYS_PWR_REG. */ exynos_mcpm_down_handler(SKIP_CPU_POWERDOWN_IF_CPU0); } And SKIP_CPU_POWERDOWN_IF_CPU0 is defined in and visible to mcpm-exynos.c only. Sorry if I am being dense, but the exynos_mcpm_suspend function would get called from both the bL cpuidle driver as well the exynos pm code. What is that exynos pm code actually doing? exynos pm code is shared across Exynos4 and 5 SoCs. It primarily does a series of register configurations which are required to put the system to sleep (some parts of these are SoC specific and others common). It also populates the suspend_ops for exynos. In the current patch, exynos_suspend_enter() is where I have plugged in the mcpm_cpu_suspend call. This patch is based on the S2R series for 5420 (http://comments.gmane.org/gmane.linux.kernel.samsung-soc/33898), you may also have a look at that for a clearer picture. We want to skip CPU0 only in case of the S2R case i.e. the pm code and keep the CPU0 power down code for all other cases including CPUIdle. OK. If so I missed that somehow (hint hint). If I call exynos_mcpm_down_handler with the flag in