From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751896AbcF0Q31 (ORCPT ); Mon, 27 Jun 2016 12:29:27 -0400 Received: from mail-wm0-f49.google.com ([74.125.82.49]:38488 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751749AbcF0Q3Z (ORCPT ); Mon, 27 Jun 2016 12:29:25 -0400 Subject: Re: [PATCH v6 4/5] arm64: add support for ACPI Low Power Idle(LPI) To: Lorenzo Pieralisi , Sudeep Holla References: <1465915719-8409-1-git-send-email-sudeep.holla@arm.com> <1465915719-8409-5-git-send-email-sudeep.holla@arm.com> <20160622141700.GB2733@red-moon> Cc: "Rafael J . Wysocki" , linux-acpi@vger.kernel.org, Vikas Sajjan , Sunil , Prashanth Prakash , Al Stone , Ashwin Chaugule , linux-kernel@vger.kernel.org, Mark Rutland , linux-arm-kernel@lists.infradead.org From: Daniel Lezcano Message-ID: <57715463.5040305@linaro.org> Date: Mon, 27 Jun 2016 18:29:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20160622141700.GB2733@red-moon> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/22/2016 04:17 PM, Lorenzo Pieralisi wrote: > Hi Sudeep, > > On Tue, Jun 14, 2016 at 03:48:38PM +0100, Sudeep Holla wrote: >> This patch adds appropriate callbacks to support ACPI Low Power Idle >> (LPI) on ARM64. >> >> Now that arm_enter_idle_state is exactly same in both generic ARM{32,64} >> CPUIdle driver and ARM64 backend for ACPI processor idle driver, we can >> unify it and move to cpuidle-arm.h header. >> >> Cc: Lorenzo Pieralisi >> Cc: Mark Rutland >> Cc: Daniel Lezcano >> Cc: "Rafael J. Wysocki" >> Cc: linux-arm-kernel@lists.infradead.org >> Signed-off-by: Sudeep Holla >> --- >> arch/arm64/kernel/cpuidle.c | 17 +++++++++++++ >> drivers/cpuidle/cpuidle-arm.c | 23 ++---------------- >> drivers/firmware/psci.c | 56 +++++++++++++++++++++++++++++++++++++++++++ >> include/linux/cpuidle-arm.h | 30 +++++++++++++++++++++++ >> 4 files changed, 105 insertions(+), 21 deletions(-) >> create mode 100644 include/linux/cpuidle-arm.h > > This patch seems fine by me, it would be good if Daniel can have > a look too. > > Some minor comments below. > > [...] > >> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c >> index 03e04582791c..c6caa863d156 100644 >> --- a/drivers/firmware/psci.c >> +++ b/drivers/firmware/psci.c >> @@ -13,6 +13,7 @@ >> >> #define pr_fmt(fmt) "psci: " fmt >> >> +#include >> #include >> #include >> #include >> @@ -310,11 +311,66 @@ static int psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu) >> return ret; >> } >> >> +#ifdef CONFIG_ACPI >> +#include >> + >> +static int __maybe_unused psci_acpi_cpu_init_idle(unsigned int cpu) >> +{ >> + int i, count; >> + u32 *psci_states; >> + struct acpi_processor *pr; >> + struct acpi_lpi_state *lpi; >> + >> + pr = per_cpu(processors, cpu); >> + if (unlikely(!pr || !pr->flags.has_lpi)) >> + return -EINVAL; >> + >> + /* >> + * If the PSCI cpu_suspend function hook has not been initialized >> + * idle states must not be enabled, so bail out >> + */ >> + if (!psci_ops.cpu_suspend) >> + return -EOPNOTSUPP; >> + >> + count = pr->power.count - 1; >> + if (count <= 0) >> + return -ENODEV; >> + >> + psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL); >> + if (!psci_states) >> + return -ENOMEM; >> + >> + for (i = 0; i < count; i++) { >> + u32 state; >> + >> + lpi = &pr->power.lpi_states[i + 1]; >> + state = lpi->address & 0xFFFFFFFF; Why mask 'address' if 'state' is u32 ? >> + if (!psci_power_state_is_valid(state)) { >> + pr_warn("Invalid PSCI power state %#x\n", state); >> + kfree(psci_states); >> + return -EINVAL; >> + } >> + psci_states[i] = state; >> + } >> + /* Idle states parsed correctly, initialize per-cpu pointer */ >> + per_cpu(psci_power_state, cpu) = psci_states; >> + return 0; The ACPI and the PSCI code are not self contained here. It would be nice to move this function to the ACPI code. >> +} >> +#else >> +static int __maybe_unused psci_acpi_cpu_init_idle(unsigned int cpu) >> +{ >> + return -EINVAL; >> +} >> +#endif >> + >> int psci_cpu_init_idle(unsigned int cpu) >> { >> struct device_node *cpu_node; >> int ret; >> >> + if (!acpi_disabled) >> + return psci_acpi_cpu_init_idle(cpu); >> + acpi_disabled - acpi_disabled - acpi_disabled everywhere :/ The enable-method approach is not straightforward and now it is polluted by acpi-disabled. So IIUC, smp_init_cpus (contains acpi_disabled) smp_cpu_setup cpu_read_ops cpu_read_enable_method (contains acpi_disabled) acpi_get_enable_method (returns 'psci' after checking psci_is_present) Then psci_cpu_init_idle is called... and check again acpi_disabled. IMO, the circumlocution with the psci vs acpi vs acpi_disabled is getting unnecessary too complex, is prone to error and will lead to unmaintainable code very soon. I suggest to sort out encapsulation and self-contained code before adding more feature in this area. >> cpu_node = of_get_cpu_node(cpu, NULL); >> if (!cpu_node) >> return -ENODEV; >> diff --git a/include/linux/cpuidle-arm.h b/include/linux/cpuidle-arm.h >> new file mode 100644 >> index 000000000000..b99bcb3f43dd >> --- /dev/null >> +++ b/include/linux/cpuidle-arm.h > > arm-cpuidle.h for consistency with other (ARM) include/linux files ? > >> @@ -0,0 +1,30 @@ >> +#include >> + >> +#include >> + >> +/* >> + * arm_enter_idle_state - Programs CPU to enter the specified state >> + */ >> +static int arm_generic_enter_idle_state(int idx) >> +{ >> + int ret; >> + >> + if (!idx) { >> + cpu_do_idle(); >> + return idx; >> + } >> + >> + ret = cpu_pm_enter(); >> + if (!ret) { >> + /* >> + * Pass idle state index to cpu_suspend which in turn will >> + * call the CPU ops suspend protocol with idle index as a >> + * parameter. >> + */ >> + ret = arm_cpuidle_suspend(idx); >> + >> + cpu_pm_exit(); >> + } >> + >> + return ret ? -1 : idx; >> +} > > Either you do this, or we have to add it somehow somewhere in > drivers/cpuidle to avoid duplicating it. > > @Daniel: do you have an opinion on this please ? I don't like the idea to add an ARM arch specific header in include/linux. I thought this directory was supposed to contain as much as possible arch agnostic headers. May be the name can be changed to something more generic: eg. int cpuidle_generic_enter(int idx); and then add an option: HAVE_CPUIDLE_GENERIC_ENTER , then in the generic header: #ifdef HAVE_CPUIDLE_GENERIC_ENTER int cpuidle_generic_enter(int idx); #endif , change the function name in cpuidle-arm .c and finally add in the ARM and ARM64 Kconfig's option HAVE_CPUIDLE_GENERIC_ENTER. -- Daniel -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog