From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753538AbbCWW6g (ORCPT ); Mon, 23 Mar 2015 18:58:36 -0400 Received: from foss.arm.com ([217.140.101.70]:46949 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753187AbbCWW6d (ORCPT ); Mon, 23 Mar 2015 18:58:33 -0400 Date: Mon, 23 Mar 2015 22:58:28 +0000 From: Lorenzo Pieralisi To: Daniel Lezcano Cc: "rjw@rjwysocki.net" , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Catalin Marinas , "robherring2@gmail.com" , "arnd@arndb.de" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "lina.iyer@linaro.org" , "sboyd@codeaurora.org" Subject: Re: [PATCH V4] ARM: cpuidle: Register per cpuidle device Message-ID: <20150323225828.GC15435@e102568-lin.cambridge.arm.com> References: <20150323162514.GE18904@red-moon> <1427129424-17175-1-git-send-email-daniel.lezcano@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1427129424-17175-1-git-send-email-daniel.lezcano@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 23, 2015 at 04:50:24PM +0000, Daniel Lezcano wrote: > On some platforms, the low level PM code may not be initialized correctly for > a specific cpu. In this case, the EXNIO tells the cpuidle driver to not "-ENXIO", but honestly these sentences should be rewritten, I understand what you mean, but for someone who has not reviewed the code before this log means precious little. "If the cpuidle init cpu operation returns -ENXIO, therefore reporting HW failure or misconfiguration, the CPUidle driver skips the respective cpuidle device initialization because the associated platform back-end HW is not operational". > initialize the cpuidle device as the associated low level PM is not operational. > > That prevents the system to crash and allows to handle the error gracefully. > > For example, on Qcom's platform, each core has a SPM. The device associated > with this SPM is initialized before the cpuidle framework. If there is an error > in the initialization (eg. error in the DT), the system continues to boot but > in degraded mode as some SPM may not be correctly initialized. > > Signed-off-by: Daniel Lezcano > --- > drivers/cpuidle/cpuidle-arm.c | 46 +++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 44 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c > index 1c94b88..a7a01ce 100644 > --- a/drivers/cpuidle/cpuidle-arm.c > +++ b/drivers/cpuidle/cpuidle-arm.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > > #include > > @@ -94,6 +95,7 @@ static int __init arm_idle_init(void) > { > int cpu, ret; > struct cpuidle_driver *drv = &arm_idle_driver; > + struct cpuidle_device *dev; > > /* > * Initialize idle states data, starting at index 1. > @@ -105,18 +107,58 @@ static int __init arm_idle_init(void) > if (ret <= 0) > return ret ? : -ENODEV; > > + ret = cpuidle_register_driver(drv); > + if (ret) { > + pr_err("Failed to register cpuidle driver\n"); > + return ret; > + } > + > /* > * Call arch CPU operations in order to initialize > * idle states suspend back-end specific data > */ > for_each_possible_cpu(cpu) { > ret = arm_cpuidle_init(cpu); > + > + /* > + * Do not register the cpuidle device. This situation could > + * happen when the low level PM was not able to initialize > + * for any reaon. s/reaon/reason. I disagree, it is not for *any* reason. Something like: /* * Skip the cpuidle device initialization if the reported failure * is a HW misconfiguration/breakage (-ENXIO). */ arm_cpuidle_init() should be documented in this respect. > + */ > + if (ret == -ENXIO) > + continue; > + > if (ret) { > pr_err("CPU %d failed to init idle CPU ops\n", cpu); > - return ret; > + goto out_fail; > + } > + > + dev = kzalloc(sizeof(*dev), GFP_KERNEL); > + if (!dev) { > + pr_err("Failed to allocate cpuidle device\n"); > + goto out_fail; > + } > + dev->cpu = cpu; > + > + ret = cpuidle_register_device(dev); > + if (ret) { > + pr_err("Failed to register cpuidle device for CPU %d\n", > + cpu); > + kfree(dev); > + goto out_fail; > } > } > > - return cpuidle_register(drv, NULL); > + return 0; > +out_fail: > + while (--cpu >= 0) { > + dev = per_cpu(cpuidle_devices, cpu); > + cpuidle_unregister_device(dev); > + kfree(dev); > + } > + > + cpuidle_unregister_driver(drv); > + > + return ret; > } > device_initcall(arm_idle_init); With the changes requested: Acked-by: Lorenzo Pieralisi From mboxrd@z Thu Jan 1 00:00:00 1970 From: lorenzo.pieralisi@arm.com (Lorenzo Pieralisi) Date: Mon, 23 Mar 2015 22:58:28 +0000 Subject: [PATCH V4] ARM: cpuidle: Register per cpuidle device In-Reply-To: <1427129424-17175-1-git-send-email-daniel.lezcano@linaro.org> References: <20150323162514.GE18904@red-moon> <1427129424-17175-1-git-send-email-daniel.lezcano@linaro.org> Message-ID: <20150323225828.GC15435@e102568-lin.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Mar 23, 2015 at 04:50:24PM +0000, Daniel Lezcano wrote: > On some platforms, the low level PM code may not be initialized correctly for > a specific cpu. In this case, the EXNIO tells the cpuidle driver to not "-ENXIO", but honestly these sentences should be rewritten, I understand what you mean, but for someone who has not reviewed the code before this log means precious little. "If the cpuidle init cpu operation returns -ENXIO, therefore reporting HW failure or misconfiguration, the CPUidle driver skips the respective cpuidle device initialization because the associated platform back-end HW is not operational". > initialize the cpuidle device as the associated low level PM is not operational. > > That prevents the system to crash and allows to handle the error gracefully. > > For example, on Qcom's platform, each core has a SPM. The device associated > with this SPM is initialized before the cpuidle framework. If there is an error > in the initialization (eg. error in the DT), the system continues to boot but > in degraded mode as some SPM may not be correctly initialized. > > Signed-off-by: Daniel Lezcano > --- > drivers/cpuidle/cpuidle-arm.c | 46 +++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 44 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c > index 1c94b88..a7a01ce 100644 > --- a/drivers/cpuidle/cpuidle-arm.c > +++ b/drivers/cpuidle/cpuidle-arm.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > > #include > > @@ -94,6 +95,7 @@ static int __init arm_idle_init(void) > { > int cpu, ret; > struct cpuidle_driver *drv = &arm_idle_driver; > + struct cpuidle_device *dev; > > /* > * Initialize idle states data, starting at index 1. > @@ -105,18 +107,58 @@ static int __init arm_idle_init(void) > if (ret <= 0) > return ret ? : -ENODEV; > > + ret = cpuidle_register_driver(drv); > + if (ret) { > + pr_err("Failed to register cpuidle driver\n"); > + return ret; > + } > + > /* > * Call arch CPU operations in order to initialize > * idle states suspend back-end specific data > */ > for_each_possible_cpu(cpu) { > ret = arm_cpuidle_init(cpu); > + > + /* > + * Do not register the cpuidle device. This situation could > + * happen when the low level PM was not able to initialize > + * for any reaon. s/reaon/reason. I disagree, it is not for *any* reason. Something like: /* * Skip the cpuidle device initialization if the reported failure * is a HW misconfiguration/breakage (-ENXIO). */ arm_cpuidle_init() should be documented in this respect. > + */ > + if (ret == -ENXIO) > + continue; > + > if (ret) { > pr_err("CPU %d failed to init idle CPU ops\n", cpu); > - return ret; > + goto out_fail; > + } > + > + dev = kzalloc(sizeof(*dev), GFP_KERNEL); > + if (!dev) { > + pr_err("Failed to allocate cpuidle device\n"); > + goto out_fail; > + } > + dev->cpu = cpu; > + > + ret = cpuidle_register_device(dev); > + if (ret) { > + pr_err("Failed to register cpuidle device for CPU %d\n", > + cpu); > + kfree(dev); > + goto out_fail; > } > } > > - return cpuidle_register(drv, NULL); > + return 0; > +out_fail: > + while (--cpu >= 0) { > + dev = per_cpu(cpuidle_devices, cpu); > + cpuidle_unregister_device(dev); > + kfree(dev); > + } > + > + cpuidle_unregister_driver(drv); > + > + return ret; > } > device_initcall(arm_idle_init); With the changes requested: Acked-by: Lorenzo Pieralisi