| Message ID | 1627118399-125388-1-git-send-email-zhouyanjie@wanyeetech.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | cpuidle: JZ4780: Add Ingenic JZ4780 cpuidle driver. | expand |
Hi Zhou, Le sam., juil. 24 2021 at 17:19:59 +0800, 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com> a écrit : > The JZ4780 has a high overhead to executing a MIPS wait on SMP, as a > core must flush out dirty cache lines from its data cache before doing > so. This is because the core clock is gated during a wait and if the > other core tries to access a dirty line from the waiting core's cache, > it will lock up. > > To mitigate some of this impact, this driver provides a simple polling > top level idle state, to try to avoid the cache flushing overhead when > the wait will only be short. The second level state is implemented > with > the MIPS wait instruction. > > This patch first found in the github repository of CI20, the original > author is Alex Smith. Because there is a chance to cause kernel hang > scenarios which can occur within hours or even within days, so this > patch was abandoned, but now it is determined that this is not the > problem caused by this patch, but caused by the cache driver. With > the new Ingenic specific cache driver, it has been working properly > on CI20 v1 for more than one week. > > Tested-by: H. Nikolaus Schaller <hns@goldelico.com> > Signed-off-by: Alex Smith <alex.smith@imgtec.com> > Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com> > --- > drivers/cpuidle/Kconfig.mips | 8 +++++ > drivers/cpuidle/Makefile | 1 + > drivers/cpuidle/cpuidle-jz4780.c | 74 > ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 83 insertions(+) > create mode 100644 drivers/cpuidle/cpuidle-jz4780.c > > diff --git a/drivers/cpuidle/Kconfig.mips > b/drivers/cpuidle/Kconfig.mips > index c3c011a..4a55d24 100644 > --- a/drivers/cpuidle/Kconfig.mips > +++ b/drivers/cpuidle/Kconfig.mips > @@ -16,3 +16,11 @@ config MIPS_CPS_CPUIDLE > Processing System (CPS) architecture. In order to make use of > the deepest idle states you will need to ensure that you are > also using the CONFIG_MIPS_CPS SMP implementation. > + > +config MIPS_JZ4780_CPUIDLE > + bool "CPU Idle driver for Ingenic JZ4780" > + depends on MACH_JZ4780 && SMP > + default y > + help > + Select this option to enable CPU idle state management through > + cpuidle for Ingenic JZ4780 platforms. > diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile > index 26bbc5e..1dd372f 100644 > --- a/drivers/cpuidle/Makefile > +++ b/drivers/cpuidle/Makefile > @@ -29,6 +29,7 @@ obj-$(CONFIG_ARM_QCOM_SPM_CPUIDLE) += > cpuidle-qcom-spm.o > > ############################################################################### > # MIPS drivers > obj-$(CONFIG_MIPS_CPS_CPUIDLE) += cpuidle-cps.o > +obj-$(CONFIG_MIPS_JZ4780_CPUIDLE) += cpuidle-jz4780.o > > > ############################################################################### > # POWERPC drivers > diff --git a/drivers/cpuidle/cpuidle-jz4780.c > b/drivers/cpuidle/cpuidle-jz4780.c > new file mode 100644 > index 00000000..2025de4 > --- /dev/null > +++ b/drivers/cpuidle/cpuidle-jz4780.c > @@ -0,0 +1,74 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * JZ4780 CPU idle driver > + * Copyright (C) 2015 Imagination Technologies > + * Author: Alex Smith <alex.smith@imgtec.com> > + * Copyright (c) 2020 周琰杰 (Zhou Yanjie) > <zhouyanjie@wanyeetech.com> > + */ > + > +#include <linux/cpuidle.h> > +#include <linux/init.h> > +#include <linux/sched.h> > +#include <linux/sched/idle.h> > + > +#include <asm/idle.h> > +#include <asm/mipsregs.h> > + > +/* > + * The JZ4780 has a high overhead to entering just the basic MIPS > wait on SMP, > + * due to the requirement to flush out dirty lines from the dcache > before > + * waiting. Therefore, we try to mitigate this overhead by using a > simple > + * polling loop for short waits. > + */ > +static int jz4780_cpuidle_poll_enter(struct cpuidle_device *dev, > + struct cpuidle_driver *drv, int index) > +{ > + if (!current_set_polling_and_test()) > + while (!need_resched() && !(read_c0_cause() & read_c0_status() & > CAUSEF_IP)) > + cpu_relax(); > + > + current_clr_polling(); > + local_irq_enable(); > + > + return index; > +} > + > +static struct cpuidle_driver jz4780_cpuidle_driver = { > + .name = "jz4780_cpuidle", > + .owner = THIS_MODULE, > + .states = { > + { > + .enter = jz4780_cpuidle_poll_enter, > + .exit_latency = 1, > + .target_residency = 1, > + .power_usage = UINT_MAX, > + .name = "poll", > + .desc = "polling loop", > + }, > + { > + .enter = mips_cpuidle_wait_enter, > + .exit_latency = 50, > + .target_residency = 300, > + .power_usage = UINT_MAX, > + .name = "wait", > + .desc = "MIPS wait", > + }, > + }, > + .state_count = 2, > +}; > + > +static int __init jz4780_cpuidle_init(void) > +{ > + int ret; > + > + ret = cpuidle_register(&jz4780_cpuidle_driver, NULL); You're missing something here - you never check that the kernel is actually running on a JZ4780. Cheers, -Paul > + if (ret) { > + pr_err("Failed to register JZ4780 idle driver: %d\n", ret); > + return ret; > + } > + > + pr_info("JZ4780 idle driver registered\n"); > + > + return 0; > +} > +device_initcall(jz4780_cpuidle_init); > -- > 2.7.4 >
Hi Paul, On 2021/7/24 下午7:16, Paul Cercueil wrote: > Hi Zhou, > > Le sam., juil. 24 2021 at 17:19:59 +0800, 周琰杰 (Zhou Yanjie) > <zhouyanjie@wanyeetech.com> a écrit : >> The JZ4780 has a high overhead to executing a MIPS wait on SMP, as a >> core must flush out dirty cache lines from its data cache before doing >> so. This is because the core clock is gated during a wait and if the >> other core tries to access a dirty line from the waiting core's cache, >> it will lock up. >> >> To mitigate some of this impact, this driver provides a simple polling >> top level idle state, to try to avoid the cache flushing overhead when >> the wait will only be short. The second level state is implemented with >> the MIPS wait instruction. >> >> This patch first found in the github repository of CI20, the original >> author is Alex Smith. Because there is a chance to cause kernel hang >> scenarios which can occur within hours or even within days, so this >> patch was abandoned, but now it is determined that this is not the >> problem caused by this patch, but caused by the cache driver. With >> the new Ingenic specific cache driver, it has been working properly >> on CI20 v1 for more than one week. >> >> Tested-by: H. Nikolaus Schaller <hns@goldelico.com> >> Signed-off-by: Alex Smith <alex.smith@imgtec.com> >> Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com> >> --- >> drivers/cpuidle/Kconfig.mips | 8 +++++ >> drivers/cpuidle/Makefile | 1 + >> drivers/cpuidle/cpuidle-jz4780.c | 74 >> ++++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 83 insertions(+) >> create mode 100644 drivers/cpuidle/cpuidle-jz4780.c >> >> diff --git a/drivers/cpuidle/Kconfig.mips b/drivers/cpuidle/Kconfig.mips >> index c3c011a..4a55d24 100644 >> --- a/drivers/cpuidle/Kconfig.mips >> +++ b/drivers/cpuidle/Kconfig.mips >> @@ -16,3 +16,11 @@ config MIPS_CPS_CPUIDLE >> Processing System (CPS) architecture. In order to make use of >> the deepest idle states you will need to ensure that you are >> also using the CONFIG_MIPS_CPS SMP implementation. >> + >> +config MIPS_JZ4780_CPUIDLE >> + bool "CPU Idle driver for Ingenic JZ4780" >> + depends on MACH_JZ4780 && SMP >> + default y >> + help >> + Select this option to enable CPU idle state management through >> + cpuidle for Ingenic JZ4780 platforms. >> diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile >> index 26bbc5e..1dd372f 100644 >> --- a/drivers/cpuidle/Makefile >> +++ b/drivers/cpuidle/Makefile >> @@ -29,6 +29,7 @@ obj-$(CONFIG_ARM_QCOM_SPM_CPUIDLE) += >> cpuidle-qcom-spm.o >> >> ############################################################################### >> >> # MIPS drivers >> obj-$(CONFIG_MIPS_CPS_CPUIDLE) += cpuidle-cps.o >> +obj-$(CONFIG_MIPS_JZ4780_CPUIDLE) += cpuidle-jz4780.o >> >> >> ############################################################################### >> >> # POWERPC drivers >> diff --git a/drivers/cpuidle/cpuidle-jz4780.c >> b/drivers/cpuidle/cpuidle-jz4780.c >> new file mode 100644 >> index 00000000..2025de4 >> --- /dev/null >> +++ b/drivers/cpuidle/cpuidle-jz4780.c >> @@ -0,0 +1,74 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* >> + * JZ4780 CPU idle driver >> + * Copyright (C) 2015 Imagination Technologies >> + * Author: Alex Smith <alex.smith@imgtec.com> >> + * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com> >> + */ >> + >> +#include <linux/cpuidle.h> >> +#include <linux/init.h> >> +#include <linux/sched.h> >> +#include <linux/sched/idle.h> >> + >> +#include <asm/idle.h> >> +#include <asm/mipsregs.h> >> + >> +/* >> + * The JZ4780 has a high overhead to entering just the basic MIPS >> wait on SMP, >> + * due to the requirement to flush out dirty lines from the dcache >> before >> + * waiting. Therefore, we try to mitigate this overhead by using a >> simple >> + * polling loop for short waits. >> + */ >> +static int jz4780_cpuidle_poll_enter(struct cpuidle_device *dev, >> + struct cpuidle_driver *drv, int index) >> +{ >> + if (!current_set_polling_and_test()) >> + while (!need_resched() && !(read_c0_cause() & >> read_c0_status() & CAUSEF_IP)) >> + cpu_relax(); >> + >> + current_clr_polling(); >> + local_irq_enable(); >> + >> + return index; >> +} >> + >> +static struct cpuidle_driver jz4780_cpuidle_driver = { >> + .name = "jz4780_cpuidle", >> + .owner = THIS_MODULE, >> + .states = { >> + { >> + .enter = jz4780_cpuidle_poll_enter, >> + .exit_latency = 1, >> + .target_residency = 1, >> + .power_usage = UINT_MAX, >> + .name = "poll", >> + .desc = "polling loop", >> + }, >> + { >> + .enter = mips_cpuidle_wait_enter, >> + .exit_latency = 50, >> + .target_residency = 300, >> + .power_usage = UINT_MAX, >> + .name = "wait", >> + .desc = "MIPS wait", >> + }, >> + }, >> + .state_count = 2, >> +}; >> + >> +static int __init jz4780_cpuidle_init(void) >> +{ >> + int ret; >> + >> + ret = cpuidle_register(&jz4780_cpuidle_driver, NULL); > > You're missing something here - you never check that the kernel is > actually running on a JZ4780. Sure, I will try to fix it. Thanks and best regards! > > Cheers, > -Paul > >> + if (ret) { >> + pr_err("Failed to register JZ4780 idle driver: %d\n", ret); >> + return ret; >> + } >> + >> + pr_info("JZ4780 idle driver registered\n"); >> + >> + return 0; >> +} >> +device_initcall(jz4780_cpuidle_init); >> -- >> 2.7.4 >> >
diff --git a/drivers/cpuidle/Kconfig.mips b/drivers/cpuidle/Kconfig.mips index c3c011a..4a55d24 100644 --- a/drivers/cpuidle/Kconfig.mips +++ b/drivers/cpuidle/Kconfig.mips @@ -16,3 +16,11 @@ config MIPS_CPS_CPUIDLE Processing System (CPS) architecture. In order to make use of the deepest idle states you will need to ensure that you are also using the CONFIG_MIPS_CPS SMP implementation. + +config MIPS_JZ4780_CPUIDLE + bool "CPU Idle driver for Ingenic JZ4780" + depends on MACH_JZ4780 && SMP + default y + help + Select this option to enable CPU idle state management through + cpuidle for Ingenic JZ4780 platforms. diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile index 26bbc5e..1dd372f 100644 --- a/drivers/cpuidle/Makefile +++ b/drivers/cpuidle/Makefile @@ -29,6 +29,7 @@ obj-$(CONFIG_ARM_QCOM_SPM_CPUIDLE) += cpuidle-qcom-spm.o ############################################################################### # MIPS drivers obj-$(CONFIG_MIPS_CPS_CPUIDLE) += cpuidle-cps.o +obj-$(CONFIG_MIPS_JZ4780_CPUIDLE) += cpuidle-jz4780.o ############################################################################### # POWERPC drivers diff --git a/drivers/cpuidle/cpuidle-jz4780.c b/drivers/cpuidle/cpuidle-jz4780.c new file mode 100644 index 00000000..2025de4 --- /dev/null +++ b/drivers/cpuidle/cpuidle-jz4780.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * JZ4780 CPU idle driver + * Copyright (C) 2015 Imagination Technologies + * Author: Alex Smith <alex.smith@imgtec.com> + * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com> + */ + +#include <linux/cpuidle.h> +#include <linux/init.h> +#include <linux/sched.h> +#include <linux/sched/idle.h> + +#include <asm/idle.h> +#include <asm/mipsregs.h> + +/* + * The JZ4780 has a high overhead to entering just the basic MIPS wait on SMP, + * due to the requirement to flush out dirty lines from the dcache before + * waiting. Therefore, we try to mitigate this overhead by using a simple + * polling loop for short waits. + */ +static int jz4780_cpuidle_poll_enter(struct cpuidle_device *dev, + struct cpuidle_driver *drv, int index) +{ + if (!current_set_polling_and_test()) + while (!need_resched() && !(read_c0_cause() & read_c0_status() & CAUSEF_IP)) + cpu_relax(); + + current_clr_polling(); + local_irq_enable(); + + return index; +} + +static struct cpuidle_driver jz4780_cpuidle_driver = { + .name = "jz4780_cpuidle", + .owner = THIS_MODULE, + .states = { + { + .enter = jz4780_cpuidle_poll_enter, + .exit_latency = 1, + .target_residency = 1, + .power_usage = UINT_MAX, + .name = "poll", + .desc = "polling loop", + }, + { + .enter = mips_cpuidle_wait_enter, + .exit_latency = 50, + .target_residency = 300, + .power_usage = UINT_MAX, + .name = "wait", + .desc = "MIPS wait", + }, + }, + .state_count = 2, +}; + +static int __init jz4780_cpuidle_init(void) +{ + int ret; + + ret = cpuidle_register(&jz4780_cpuidle_driver, NULL); + if (ret) { + pr_err("Failed to register JZ4780 idle driver: %d\n", ret); + return ret; + } + + pr_info("JZ4780 idle driver registered\n"); + + return 0; +} +device_initcall(jz4780_cpuidle_init);