| Message ID | 1429200617-9546-2-git-send-email-lorenzo.pieralisi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04/16/2015 06:10 PM, Lorenzo Pieralisi wrote: > Some ARM systems (eg big.LITTLE ones) can be composed of CPUs having > different hardware power management configurations and in the context > of CPUidle, different idle states. The generic ARM CPUidle driver > treats all possible CPUs as equal and initializes a common idle driver > through DT idle states for all possible CPUs. > > Current driver cannot manage systems where CPUs are heterogeneous > and therefore can have different idle states. > > This patch augments the generic ARM CPUidle driver, by adding code that > at boot initializes CPUidle drivers by going through the > cpu_possible_mask and through DT parsing detects the cpus sharing the > same idle states, thus creating the CPUidle drivers cpumasks. > > The drivers are then initialized through the DT idle states interface, > that parses and initializes the DT idle states for the cpus set in the > drivers cpumasks. > > This patch instantiates a static array of idle drivers, some of which > can turn out to be unused (eg platforms with uniform idle states > on all possible CPUs), and relies on the config option > CPU_IDLE_MULTIPLE_DRIVERS to be selected by default; this can cause a > little memory overhead, but at the same time allows supporting most of > the current and future ARM platforms through a single generic CPUidle > driver. > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > Cc: Howard Chen <howard.chen@linaro.org> > Cc: Rob Herring <robh+dt@kernel.org> > Cc: Kevin Hilman <khilman@linaro.org> > Cc: Sudeep Holla <sudeep.holla@arm.com> > Cc: Lina Iyer <lina.iyer@linaro.org> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > Cc: Grant Likely <grant.likely@linaro.org> > Cc: Mathieu Poirier <mathieu.poirier@linaro.org> > Cc: Mark Rutland <mark.rutland@arm.com> > --- > drivers/cpuidle/Kconfig.arm | 1 + > drivers/cpuidle/cpuidle-arm.c | 176 ++++++++++++++++++++++++++++++++++++------ > 2 files changed, 152 insertions(+), 25 deletions(-) > > diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm > index 21340e0..90c6553 100644 > --- a/drivers/cpuidle/Kconfig.arm > +++ b/drivers/cpuidle/Kconfig.arm > @@ -3,6 +3,7 @@ > # > config ARM_CPUIDLE > bool "Generic ARM/ARM64 CPU idle Driver" > + select CPU_IDLE_MULTIPLE_DRIVERS > select DT_IDLE_STATES > help > Select this to enable generic cpuidle driver for ARM. > diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c > index 545069d..251fa2a 100644 > --- a/drivers/cpuidle/cpuidle-arm.c > +++ b/drivers/cpuidle/cpuidle-arm.c > @@ -14,6 +14,7 @@ > #include <linux/cpuidle.h> > #include <linux/cpumask.h> > #include <linux/cpu_pm.h> > +#include <linux/of_device.h> > #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/of.h> > @@ -58,23 +59,27 @@ static int arm_enter_idle_state(struct cpuidle_device *dev, > return ret ? -1 : idx; > } > > -static struct cpuidle_driver arm_idle_driver = { > - .name = "arm_idle", > - .owner = THIS_MODULE, > - /* > - * State at index 0 is standby wfi and considered standard > - * on all ARM platforms. If in some platforms simple wfi > - * can't be used as "state 0", DT bindings must be implemented > - * to work around this issue and allow installing a special > - * handler for idle state index 0. > - */ > - .states[0] = { > - .enter = arm_enter_idle_state, > - .exit_latency = 1, > - .target_residency = 1, > - .power_usage = UINT_MAX, > - .name = "WFI", > - .desc = "ARM WFI", > +#define ARM_CPUIDLE_MAX_DRIVERS 2 > + > +static struct cpuidle_driver arm_idle_drivers[ARM_CPUIDLE_MAX_DRIVERS] = { > + [0 ... ARM_CPUIDLE_MAX_DRIVERS - 1] = { > + .name = "arm_idle", > + .owner = THIS_MODULE, > + /* > + * State at index 0 is standby wfi and considered standard > + * on all ARM platforms. If in some platforms simple wfi > + * can't be used as "state 0", DT bindings must be implemented > + * to work around this issue and allow installing a special > + * handler for idle state index 0. > + */ > + .states[0] = { > + .enter = arm_enter_idle_state, > + .exit_latency = 1, > + .target_residency = 1, > + .power_usage = UINT_MAX, > + .name = "WFI", > + .desc = "ARM WFI", > + } > } > }; > > @@ -85,17 +90,68 @@ static const struct of_device_id arm_idle_state_match[] __initconst = { > }; > > /* > - * arm_idle_init > + * Compare idle states phandle properties > * > - * Registers the arm specific cpuidle driver with the cpuidle > - * framework. It relies on core code to parse the idle states > - * and initialize them using driver data structures accordingly. > + * Return true if properties are valid and equal, false otherwise Just a detail. Would be more consistent to return zero when valid and equal ? > */ > -static int __init arm_idle_init(void) > +static bool __init idle_states_cmp(struct property *states1, > + struct property *states2) > +{ > + /* > + * NB: Implemented through code from drivers/of/unittest.c > + * Function is generic and can be moved to generic OF code > + * if needed > + */ > + return states1 && states2 && > + (states1->length == states2->length) && > + states1->value && states2->value && > + !memcmp(states1->value, states2->value, states1->length); > +} > + > +static int __init arm_idle_init_driver(struct cpuidle_driver *drv) > { > - int cpu, ret; > - struct cpuidle_driver *drv = &arm_idle_driver; > + int ret, cpu; > struct cpuidle_device *dev; > + struct property *curr_idle_states, *idle_states = NULL; > + struct device_node *cpu_node; > + > + for_each_cpu(cpu, drv->cpumask) { > + cpu_node = of_cpu_device_node_get(cpu); > + curr_idle_states = of_find_property(cpu_node, > + "cpu-idle-states", NULL); > + of_node_put(cpu_node); > + > + /* > + * Stash the first valid idle states phandle in the cpumask. > + * If curr_idle_states is NULL assigning it to idle_states > + * is harmless and it is managed by idle states comparison > + * code. Keep track of first valid phandle so that > + * subsequent cpus can compare against it. > + */ > + if (!idle_states) > + idle_states = curr_idle_states; > + > + /* > + * If idle states phandles are not equal, remove the > + * cpu from the driver mask since a CPUidle driver > + * is only capable of managing uniform idle states. > + * > + * Comparison works also when idle_states and > + * curr_idle_states are the same property, since > + * they can be == NULL so the cpu must be removed from > + * the driver mask in that case too (ie cpu has no idle > + * states). > + */ > + if (!idle_states_cmp(idle_states, curr_idle_states)) > + cpumask_clear_cpu(cpu, drv->cpumask); > + } > + > + /* > + * If there are no valid states for this driver we rely on arch > + * default idle behaviour, bail out > + */ > + if (!idle_states) > + return -ENODEV; > > /* > * Initialize idle states data, starting at index 1. > @@ -117,7 +173,7 @@ static int __init arm_idle_init(void) > * Call arch CPU operations in order to initialize > * idle states suspend back-end specific data > */ > - for_each_possible_cpu(cpu) { > + for_each_cpu(cpu, drv->cpumask) { > ret = arm_cpuidle_init(cpu); > > /* > @@ -157,7 +213,77 @@ out_fail: > } > > cpuidle_unregister_driver(drv); > + return ret; > +} > + > +/* > + * arm_idle_init > + * > + * Registers the arm specific cpuidle driver(s) with the cpuidle > + * framework. It relies on core code to parse the idle states > + * and initialize them using driver data structures accordingly. > + */ > +static int __init arm_idle_init(void) > +{ > + int i, ret = -ENODEV; > + struct cpuidle_driver *drv; > + cpumask_var_t tmpmask; > + > + /* > + * These drivers require DT idle states to be present. > + * If no idle states are detected there is no reason to > + * proceed any further hence we return early. > + */ > + if (!of_find_node_by_name(NULL, "idle-states")) > + return -ENODEV; > + > + if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) > + return -ENOMEM; > + > + /* > + * We need to vet idle states to create CPUidle drivers > + * that share a common set of them. Create a tmp mask > + * that we use to keep track of initialized cpus. > + * Start off by initializing the mask with all possible > + * cpus, we clear it as we go, till either all cpus > + * have a CPUidle driver initialized or there are some > + * CPUs that have no idle states or a parsing error > + * occurs. > + */ > + cpumask_copy(tmpmask, cpu_possible_mask); > + > + for (i = 0; !cpumask_empty(tmpmask); i++) { > + if (i == ARM_CPUIDLE_MAX_DRIVERS) { > + pr_warn("number of drivers exceeding static allocation\n"); > + break; > + } > + > + drv = &arm_idle_drivers[i]; > + drv->cpumask = kzalloc(cpumask_size(), GFP_KERNEL); > + if (!drv->cpumask) { > + ret = -ENOMEM; > + break; > + } > + /* > + * Force driver mask, arm_idle_init_driver() > + * will tweak it by vetting idle states. > + */ > + cpumask_copy(drv->cpumask, tmpmask); Why do you need to copy tmpmask ? Isn't simpler to have a zero-ed cpumask and let the arm_idle_init_driver function to set a bit instead of clearing it ? > + ret = arm_idle_init_driver(drv); > + if (ret) { > + kfree(drv->cpumask); > + break; > + } > + /* > + * Remove the cpus that were part of the registered > + * driver from the mask of cpus to be initialized > + * and restart. > + */ > + cpumask_andnot(tmpmask, tmpmask, drv->cpumask); If there is a DT definition with just a cluster with the cpuidle driver set and another one without any idle state, we will have always a pr_warn because i == ARM_CPUIDLE_MAX_DRIVERS due to tmpmask being never equal to a zero mask. Is it the purpose to detect such cases ? > + } > > + free_cpumask_var(tmpmask); > return ret; > } > device_initcall(arm_idle_init); >
On Mon, May 04, 2015 at 02:19:15PM +0100, Daniel Lezcano wrote: > On 04/16/2015 06:10 PM, Lorenzo Pieralisi wrote: <snip> > > /* > > - * arm_idle_init > > + * Compare idle states phandle properties > > * > > - * Registers the arm specific cpuidle driver with the cpuidle > > - * framework. It relies on core code to parse the idle states > > - * and initialize them using driver data structures accordingly. > > + * Return true if properties are valid and equal, false otherwise > > Just a detail. Would be more consistent to return zero when valid and > equal ? Consistent with memcmp you mean ? Yes, I can change it. > > */ > > -static int __init arm_idle_init(void) > > +static bool __init idle_states_cmp(struct property *states1, > > + struct property *states2) > > +{ > > + /* > > + * NB: Implemented through code from drivers/of/unittest.c > > + * Function is generic and can be moved to generic OF code > > + * if needed > > + */ > > + return states1 && states2 && > > + (states1->length == states2->length) && > > + states1->value && states2->value && > > + !memcmp(states1->value, states2->value, states1->length); > > +} > > + > > +static int __init arm_idle_init_driver(struct cpuidle_driver *drv) > > { > > - int cpu, ret; > > - struct cpuidle_driver *drv = &arm_idle_driver; > > + int ret, cpu; > > struct cpuidle_device *dev; > > + struct property *curr_idle_states, *idle_states = NULL; > > + struct device_node *cpu_node; > > + > > + for_each_cpu(cpu, drv->cpumask) { > > + cpu_node = of_cpu_device_node_get(cpu); > > + curr_idle_states = of_find_property(cpu_node, > > + "cpu-idle-states", NULL); > > + of_node_put(cpu_node); > > + > > + /* > > + * Stash the first valid idle states phandle in the cpumask. > > + * If curr_idle_states is NULL assigning it to idle_states > > + * is harmless and it is managed by idle states comparison > > + * code. Keep track of first valid phandle so that > > + * subsequent cpus can compare against it. > > + */ > > + if (!idle_states) > > + idle_states = curr_idle_states; > > + > > + /* > > + * If idle states phandles are not equal, remove the > > + * cpu from the driver mask since a CPUidle driver > > + * is only capable of managing uniform idle states. > > + * > > + * Comparison works also when idle_states and > > + * curr_idle_states are the same property, since > > + * they can be == NULL so the cpu must be removed from > > + * the driver mask in that case too (ie cpu has no idle > > + * states). > > + */ > > + if (!idle_states_cmp(idle_states, curr_idle_states)) > > + cpumask_clear_cpu(cpu, drv->cpumask); > > + } > > + > > + /* > > + * If there are no valid states for this driver we rely on arch > > + * default idle behaviour, bail out > > + */ > > + if (!idle_states) > > + return -ENODEV; > > > > /* > > * Initialize idle states data, starting at index 1. > > @@ -117,7 +173,7 @@ static int __init arm_idle_init(void) > > * Call arch CPU operations in order to initialize > > * idle states suspend back-end specific data > > */ > > - for_each_possible_cpu(cpu) { > > + for_each_cpu(cpu, drv->cpumask) { > > ret = arm_cpuidle_init(cpu); > > > > /* > > @@ -157,7 +213,77 @@ out_fail: > > } > > > > cpuidle_unregister_driver(drv); > > + return ret; > > +} > > + > > +/* > > + * arm_idle_init > > + * > > + * Registers the arm specific cpuidle driver(s) with the cpuidle > > + * framework. It relies on core code to parse the idle states > > + * and initialize them using driver data structures accordingly. > > + */ > > +static int __init arm_idle_init(void) > > +{ > > + int i, ret = -ENODEV; > > + struct cpuidle_driver *drv; > > + cpumask_var_t tmpmask; > > + > > + /* > > + * These drivers require DT idle states to be present. > > + * If no idle states are detected there is no reason to > > + * proceed any further hence we return early. > > + */ > > + if (!of_find_node_by_name(NULL, "idle-states")) > > + return -ENODEV; > > + > > + if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) > > + return -ENOMEM; > > + > > + /* > > + * We need to vet idle states to create CPUidle drivers > > + * that share a common set of them. Create a tmp mask > > + * that we use to keep track of initialized cpus. > > + * Start off by initializing the mask with all possible > > + * cpus, we clear it as we go, till either all cpus > > + * have a CPUidle driver initialized or there are some > > + * CPUs that have no idle states or a parsing error > > + * occurs. > > + */ > > + cpumask_copy(tmpmask, cpu_possible_mask); > > + > > + for (i = 0; !cpumask_empty(tmpmask); i++) { > > + if (i == ARM_CPUIDLE_MAX_DRIVERS) { > > + pr_warn("number of drivers exceeding static allocation\n"); > > + break; > > + } > > + > > + drv = &arm_idle_drivers[i]; > > + drv->cpumask = kzalloc(cpumask_size(), GFP_KERNEL); > > + if (!drv->cpumask) { > > + ret = -ENOMEM; > > + break; > > + } > > + /* > > + * Force driver mask, arm_idle_init_driver() > > + * will tweak it by vetting idle states. > > + */ > > + cpumask_copy(drv->cpumask, tmpmask); > > Why do you need to copy tmpmask ? Isn't simpler to have a zero-ed > cpumask and let the arm_idle_init_driver function to set a bit instead > of clearing it ? No, because we need to keep track of logical cpus that have been already parsed, we need a tmpmask to keep track of that, how could we do it otherwise ? We can have more than two cpumask sets. > > > + ret = arm_idle_init_driver(drv); > > + if (ret) { > > + kfree(drv->cpumask); > > + break; > > + } > > + /* > > + * Remove the cpus that were part of the registered > > + * driver from the mask of cpus to be initialized > > + * and restart. > > + */ > > + cpumask_andnot(tmpmask, tmpmask, drv->cpumask); > > If there is a DT definition with just a cluster with the cpuidle driver > set and another one without any idle state, we will have always a > pr_warn because i == ARM_CPUIDLE_MAX_DRIVERS due to tmpmask being never > equal to a zero mask. Is it the purpose to detect such cases ? Not really, because arm_idle_init_driver() would return -ENODEV when it detects cpus with no idle states and the loop will break before warning. If we had two cluster of cpus with an idle-states set per cluster plus some cpus with no idle states the warning would be hit, because in actual facts we have more cpuidle sets than drivers (I know, a cpu set with no idle states falls back to default idle, but I think that's a detail that is easy to sort out). I can create idle drivers dynamically so that the ARM_CPUIDLE_MAX_DRIVERS check can be removed or relaxed (but the code becomes slightly more complex). Thanks for having a look, apart from these comments do we think it is a reasonable approach ? Lorenzo > > > + } > > > > + free_cpumask_var(tmpmask); > > return ret; > > } > > device_initcall(arm_idle_init); > > > > > -- > <http://www.linaro.org/> Linaro.org ??? Open source software for ARM SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog >
On Tue, May 05, 2015 at 04:56:15PM +0100, Lorenzo Pieralisi wrote: > On Mon, May 04, 2015 at 02:19:15PM +0100, Daniel Lezcano wrote: > > On 04/16/2015 06:10 PM, Lorenzo Pieralisi wrote: > > <snip> > > > > /* > > > - * arm_idle_init > > > + * Compare idle states phandle properties > > > * > > > - * Registers the arm specific cpuidle driver with the cpuidle > > > - * framework. It relies on core code to parse the idle states > > > - * and initialize them using driver data structures accordingly. > > > + * Return true if properties are valid and equal, false otherwise > > > > Just a detail. Would be more consistent to return zero when valid and > > equal ? > > Consistent with memcmp you mean ? Yes, I can change it. > > > > */ > > > -static int __init arm_idle_init(void) > > > +static bool __init idle_states_cmp(struct property *states1, > > > + struct property *states2) > > > +{ > > > + /* > > > + * NB: Implemented through code from drivers/of/unittest.c > > > + * Function is generic and can be moved to generic OF code > > > + * if needed > > > + */ > > > + return states1 && states2 && > > > + (states1->length == states2->length) && > > > + states1->value && states2->value && > > > + !memcmp(states1->value, states2->value, states1->length); > > > +} > > > + > > > +static int __init arm_idle_init_driver(struct cpuidle_driver *drv) > > > { > > > - int cpu, ret; > > > - struct cpuidle_driver *drv = &arm_idle_driver; > > > + int ret, cpu; > > > struct cpuidle_device *dev; > > > + struct property *curr_idle_states, *idle_states = NULL; > > > + struct device_node *cpu_node; > > > + > > > + for_each_cpu(cpu, drv->cpumask) { > > > + cpu_node = of_cpu_device_node_get(cpu); > > > + curr_idle_states = of_find_property(cpu_node, > > > + "cpu-idle-states", NULL); > > > + of_node_put(cpu_node); > > > + > > > + /* > > > + * Stash the first valid idle states phandle in the cpumask. > > > + * If curr_idle_states is NULL assigning it to idle_states > > > + * is harmless and it is managed by idle states comparison > > > + * code. Keep track of first valid phandle so that > > > + * subsequent cpus can compare against it. > > > + */ > > > + if (!idle_states) > > > + idle_states = curr_idle_states; > > > + > > > + /* > > > + * If idle states phandles are not equal, remove the > > > + * cpu from the driver mask since a CPUidle driver > > > + * is only capable of managing uniform idle states. > > > + * > > > + * Comparison works also when idle_states and > > > + * curr_idle_states are the same property, since > > > + * they can be == NULL so the cpu must be removed from > > > + * the driver mask in that case too (ie cpu has no idle > > > + * states). > > > + */ > > > + if (!idle_states_cmp(idle_states, curr_idle_states)) > > > + cpumask_clear_cpu(cpu, drv->cpumask); > > > + } > > > + > > > + /* > > > + * If there are no valid states for this driver we rely on arch > > > + * default idle behaviour, bail out > > > + */ > > > + if (!idle_states) > > > + return -ENODEV; > > > > > > /* > > > * Initialize idle states data, starting at index 1. > > > @@ -117,7 +173,7 @@ static int __init arm_idle_init(void) > > > * Call arch CPU operations in order to initialize > > > * idle states suspend back-end specific data > > > */ > > > - for_each_possible_cpu(cpu) { > > > + for_each_cpu(cpu, drv->cpumask) { > > > ret = arm_cpuidle_init(cpu); > > > > > > /* > > > @@ -157,7 +213,77 @@ out_fail: > > > } > > > > > > cpuidle_unregister_driver(drv); > > > + return ret; > > > +} > > > + > > > +/* > > > + * arm_idle_init > > > + * > > > + * Registers the arm specific cpuidle driver(s) with the cpuidle > > > + * framework. It relies on core code to parse the idle states > > > + * and initialize them using driver data structures accordingly. > > > + */ > > > +static int __init arm_idle_init(void) > > > +{ > > > + int i, ret = -ENODEV; > > > + struct cpuidle_driver *drv; > > > + cpumask_var_t tmpmask; > > > + > > > + /* > > > + * These drivers require DT idle states to be present. > > > + * If no idle states are detected there is no reason to > > > + * proceed any further hence we return early. > > > + */ > > > + if (!of_find_node_by_name(NULL, "idle-states")) > > > + return -ENODEV; > > > + > > > + if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) > > > + return -ENOMEM; > > > + > > > + /* > > > + * We need to vet idle states to create CPUidle drivers > > > + * that share a common set of them. Create a tmp mask > > > + * that we use to keep track of initialized cpus. > > > + * Start off by initializing the mask with all possible > > > + * cpus, we clear it as we go, till either all cpus > > > + * have a CPUidle driver initialized or there are some > > > + * CPUs that have no idle states or a parsing error > > > + * occurs. > > > + */ > > > + cpumask_copy(tmpmask, cpu_possible_mask); > > > + > > > + for (i = 0; !cpumask_empty(tmpmask); i++) { > > > + if (i == ARM_CPUIDLE_MAX_DRIVERS) { > > > + pr_warn("number of drivers exceeding static allocation\n"); > > > + break; > > > + } > > > + > > > + drv = &arm_idle_drivers[i]; > > > + drv->cpumask = kzalloc(cpumask_size(), GFP_KERNEL); > > > + if (!drv->cpumask) { > > > + ret = -ENOMEM; > > > + break; > > > + } > > > + /* > > > + * Force driver mask, arm_idle_init_driver() > > > + * will tweak it by vetting idle states. > > > + */ > > > + cpumask_copy(drv->cpumask, tmpmask); > > > > Why do you need to copy tmpmask ? Isn't simpler to have a zero-ed > > cpumask and let the arm_idle_init_driver function to set a bit instead > > of clearing it ? > > No, because we need to keep track of logical cpus that have been > already parsed, we need a tmpmask to keep track of that, how could > we do it otherwise ? We can have more than two cpumask sets. > > > > > > + ret = arm_idle_init_driver(drv); > > > + if (ret) { > > > + kfree(drv->cpumask); > > > + break; > > > + } > > > + /* > > > + * Remove the cpus that were part of the registered > > > + * driver from the mask of cpus to be initialized > > > + * and restart. > > > + */ > > > + cpumask_andnot(tmpmask, tmpmask, drv->cpumask); > > > > If there is a DT definition with just a cluster with the cpuidle driver > > set and another one without any idle state, we will have always a > > pr_warn because i == ARM_CPUIDLE_MAX_DRIVERS due to tmpmask being never > > equal to a zero mask. Is it the purpose to detect such cases ? > > Not really, because arm_idle_init_driver() would return -ENODEV when > it detects cpus with no idle states and the loop will break before warning. > > If we had two cluster of cpus with an idle-states set per cluster plus > some cpus with no idle states the warning would be hit, because > in actual facts we have more cpuidle sets than drivers (I know, a cpu > set with no idle states falls back to default idle, but I think > that's a detail that is easy to sort out). > > I can create idle drivers dynamically so that the ARM_CPUIDLE_MAX_DRIVERS > check can be removed or relaxed (but the code becomes slightly more complex). > > Thanks for having a look, apart from these comments do we think it is > a reasonable approach ? Any further comments ? I can post a v2 with an updated idle_states_cmp() return value, if we think the multiple drivers approach is valid. Thanks a lot, Lorenzo
Hi Lorenzo, On Tue, May 12, 2015 at 9:03 PM, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote: > On Tue, May 05, 2015 at 04:56:15PM +0100, Lorenzo Pieralisi wrote: >> On Mon, May 04, 2015 at 02:19:15PM +0100, Daniel Lezcano wrote: >> > On 04/16/2015 06:10 PM, Lorenzo Pieralisi wrote: >> >> <snip> >> >> > > /* >> > > - * arm_idle_init >> > > + * Compare idle states phandle properties >> > > * >> > > - * Registers the arm specific cpuidle driver with the cpuidle >> > > - * framework. It relies on core code to parse the idle states >> > > - * and initialize them using driver data structures accordingly. >> > > + * Return true if properties are valid and equal, false otherwise >> > >> > Just a detail. Would be more consistent to return zero when valid and >> > equal ? >> >> Consistent with memcmp you mean ? Yes, I can change it. >> >> > > */ >> > > -static int __init arm_idle_init(void) >> > > +static bool __init idle_states_cmp(struct property *states1, >> > > + struct property *states2) >> > > +{ >> > > + /* >> > > + * NB: Implemented through code from drivers/of/unittest.c >> > > + * Function is generic and can be moved to generic OF code >> > > + * if needed >> > > + */ >> > > + return states1 && states2 && >> > > + (states1->length == states2->length) && >> > > + states1->value && states2->value && >> > > + !memcmp(states1->value, states2->value, states1->length); >> > > +} >> > > + >> > > +static int __init arm_idle_init_driver(struct cpuidle_driver *drv) >> > > { >> > > - int cpu, ret; >> > > - struct cpuidle_driver *drv = &arm_idle_driver; >> > > + int ret, cpu; >> > > struct cpuidle_device *dev; >> > > + struct property *curr_idle_states, *idle_states = NULL; >> > > + struct device_node *cpu_node; >> > > + >> > > + for_each_cpu(cpu, drv->cpumask) { >> > > + cpu_node = of_cpu_device_node_get(cpu); >> > > + curr_idle_states = of_find_property(cpu_node, >> > > + "cpu-idle-states", NULL); >> > > + of_node_put(cpu_node); >> > > + >> > > + /* >> > > + * Stash the first valid idle states phandle in the cpumask. >> > > + * If curr_idle_states is NULL assigning it to idle_states >> > > + * is harmless and it is managed by idle states comparison >> > > + * code. Keep track of first valid phandle so that >> > > + * subsequent cpus can compare against it. >> > > + */ >> > > + if (!idle_states) >> > > + idle_states = curr_idle_states; >> > > + >> > > + /* >> > > + * If idle states phandles are not equal, remove the >> > > + * cpu from the driver mask since a CPUidle driver >> > > + * is only capable of managing uniform idle states. >> > > + * >> > > + * Comparison works also when idle_states and >> > > + * curr_idle_states are the same property, since >> > > + * they can be == NULL so the cpu must be removed from >> > > + * the driver mask in that case too (ie cpu has no idle >> > > + * states). >> > > + */ >> > > + if (!idle_states_cmp(idle_states, curr_idle_states)) >> > > + cpumask_clear_cpu(cpu, drv->cpumask); >> > > + } >> > > + >> > > + /* >> > > + * If there are no valid states for this driver we rely on arch >> > > + * default idle behaviour, bail out >> > > + */ >> > > + if (!idle_states) >> > > + return -ENODEV; >> > > >> > > /* >> > > * Initialize idle states data, starting at index 1. >> > > @@ -117,7 +173,7 @@ static int __init arm_idle_init(void) >> > > * Call arch CPU operations in order to initialize >> > > * idle states suspend back-end specific data >> > > */ >> > > - for_each_possible_cpu(cpu) { >> > > + for_each_cpu(cpu, drv->cpumask) { >> > > ret = arm_cpuidle_init(cpu); >> > > >> > > /* >> > > @@ -157,7 +213,77 @@ out_fail: >> > > } >> > > >> > > cpuidle_unregister_driver(drv); >> > > + return ret; >> > > +} >> > > + >> > > +/* >> > > + * arm_idle_init >> > > + * >> > > + * Registers the arm specific cpuidle driver(s) with the cpuidle >> > > + * framework. It relies on core code to parse the idle states >> > > + * and initialize them using driver data structures accordingly. >> > > + */ >> > > +static int __init arm_idle_init(void) >> > > +{ >> > > + int i, ret = -ENODEV; >> > > + struct cpuidle_driver *drv; >> > > + cpumask_var_t tmpmask; >> > > + >> > > + /* >> > > + * These drivers require DT idle states to be present. >> > > + * If no idle states are detected there is no reason to >> > > + * proceed any further hence we return early. >> > > + */ >> > > + if (!of_find_node_by_name(NULL, "idle-states")) >> > > + return -ENODEV; >> > > + >> > > + if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) >> > > + return -ENOMEM; >> > > + >> > > + /* >> > > + * We need to vet idle states to create CPUidle drivers >> > > + * that share a common set of them. Create a tmp mask >> > > + * that we use to keep track of initialized cpus. >> > > + * Start off by initializing the mask with all possible >> > > + * cpus, we clear it as we go, till either all cpus >> > > + * have a CPUidle driver initialized or there are some >> > > + * CPUs that have no idle states or a parsing error >> > > + * occurs. >> > > + */ >> > > + cpumask_copy(tmpmask, cpu_possible_mask); >> > > + >> > > + for (i = 0; !cpumask_empty(tmpmask); i++) { >> > > + if (i == ARM_CPUIDLE_MAX_DRIVERS) { >> > > + pr_warn("number of drivers exceeding static allocation\n"); >> > > + break; >> > > + } >> > > + >> > > + drv = &arm_idle_drivers[i]; >> > > + drv->cpumask = kzalloc(cpumask_size(), GFP_KERNEL); >> > > + if (!drv->cpumask) { >> > > + ret = -ENOMEM; >> > > + break; >> > > + } >> > > + /* >> > > + * Force driver mask, arm_idle_init_driver() >> > > + * will tweak it by vetting idle states. >> > > + */ >> > > + cpumask_copy(drv->cpumask, tmpmask); >> > >> > Why do you need to copy tmpmask ? Isn't simpler to have a zero-ed >> > cpumask and let the arm_idle_init_driver function to set a bit instead >> > of clearing it ? >> >> No, because we need to keep track of logical cpus that have been >> already parsed, we need a tmpmask to keep track of that, how could >> we do it otherwise ? We can have more than two cpumask sets. >> >> > >> > > + ret = arm_idle_init_driver(drv); >> > > + if (ret) { >> > > + kfree(drv->cpumask); >> > > + break; >> > > + } >> > > + /* >> > > + * Remove the cpus that were part of the registered >> > > + * driver from the mask of cpus to be initialized >> > > + * and restart. >> > > + */ >> > > + cpumask_andnot(tmpmask, tmpmask, drv->cpumask); >> > >> > If there is a DT definition with just a cluster with the cpuidle driver >> > set and another one without any idle state, we will have always a >> > pr_warn because i == ARM_CPUIDLE_MAX_DRIVERS due to tmpmask being never >> > equal to a zero mask. Is it the purpose to detect such cases ? >> >> Not really, because arm_idle_init_driver() would return -ENODEV when >> it detects cpus with no idle states and the loop will break before warning. >> >> If we had two cluster of cpus with an idle-states set per cluster plus >> some cpus with no idle states the warning would be hit, because >> in actual facts we have more cpuidle sets than drivers (I know, a cpu >> set with no idle states falls back to default idle, but I think >> that's a detail that is easy to sort out). >> >> I can create idle drivers dynamically so that the ARM_CPUIDLE_MAX_DRIVERS >> check can be removed or relaxed (but the code becomes slightly more complex). >> >> Thanks for having a look, apart from these comments do we think it is >> a reasonable approach ? > > Any further comments ? I can post a v2 with an updated idle_states_cmp() > return value, if we think the multiple drivers approach is valid. Can you post v2? From the silence on the list, I guess there is no strong objection to your approach. So, perhaps it is time to remove the "RFC" as well so this can get on track to be merged. -Dan > > Thanks a lot, > Lorenzo > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Hi Daniel, On Tue, Jul 14, 2015 at 05:52:48AM +0100, Daniel Kurtz wrote: [...] > > Any further comments ? I can post a v2 with an updated idle_states_cmp() > > return value, if we think the multiple drivers approach is valid. > > Can you post v2? > From the silence on the list, I guess there is no strong objection to > your approach. I just wanted to make sure this patch is strictly required before asking for a merge in the mainline, it adds to the code complexity so it should not be taken lightly. > So, perhaps it is time to remove the "RFC" as well so this can get on > track to be merged. I will drop the RFC status and add a simple configuration to define a config entry to configure the max number of drivers statically so that we do not waste memory for nothing. Thanks, Lorenzo
Hi Daniel, On Mon, May 04, 2015 at 02:19:15PM +0100, Daniel Lezcano wrote: > On 04/16/2015 06:10 PM, Lorenzo Pieralisi wrote: [...] > > /* > > - * arm_idle_init > > + * Compare idle states phandle properties > > * > > - * Registers the arm specific cpuidle driver with the cpuidle > > - * framework. It relies on core code to parse the idle states > > - * and initialize them using driver data structures accordingly. > > + * Return true if properties are valid and equal, false otherwise > > Just a detail. Would be more consistent to return zero when valid and > equal ? It is a detail but I think it is clearer as it is (ie what would it return on failure ? After all it is just used as a predicate, there is no use for a return value other than a boolean), so unless you have a strong feeling against it I would leave it as it is. Thanks, Lorenzo > > */ > > -static int __init arm_idle_init(void) > > +static bool __init idle_states_cmp(struct property *states1, > > + struct property *states2) > > +{ > > + /* > > + * NB: Implemented through code from drivers/of/unittest.c > > + * Function is generic and can be moved to generic OF code > > + * if needed > > + */ > > + return states1 && states2 && > > + (states1->length == states2->length) && > > + states1->value && states2->value && > > + !memcmp(states1->value, states2->value, states1->length); > > +} > > + > > +static int __init arm_idle_init_driver(struct cpuidle_driver *drv) > > { > > - int cpu, ret; > > - struct cpuidle_driver *drv = &arm_idle_driver; > > + int ret, cpu; > > struct cpuidle_device *dev; > > + struct property *curr_idle_states, *idle_states = NULL; > > + struct device_node *cpu_node; > > + > > + for_each_cpu(cpu, drv->cpumask) { > > + cpu_node = of_cpu_device_node_get(cpu); > > + curr_idle_states = of_find_property(cpu_node, > > + "cpu-idle-states", NULL); > > + of_node_put(cpu_node); > > + > > + /* > > + * Stash the first valid idle states phandle in the cpumask. > > + * If curr_idle_states is NULL assigning it to idle_states > > + * is harmless and it is managed by idle states comparison > > + * code. Keep track of first valid phandle so that > > + * subsequent cpus can compare against it. > > + */ > > + if (!idle_states) > > + idle_states = curr_idle_states; > > + > > + /* > > + * If idle states phandles are not equal, remove the > > + * cpu from the driver mask since a CPUidle driver > > + * is only capable of managing uniform idle states. > > + * > > + * Comparison works also when idle_states and > > + * curr_idle_states are the same property, since > > + * they can be == NULL so the cpu must be removed from > > + * the driver mask in that case too (ie cpu has no idle > > + * states). > > + */ > > + if (!idle_states_cmp(idle_states, curr_idle_states)) > > + cpumask_clear_cpu(cpu, drv->cpumask); > > + } > > + > > + /* > > + * If there are no valid states for this driver we rely on arch > > + * default idle behaviour, bail out > > + */ > > + if (!idle_states) > > + return -ENODEV; > > > > /* > > * Initialize idle states data, starting at index 1. > > @@ -117,7 +173,7 @@ static int __init arm_idle_init(void) > > * Call arch CPU operations in order to initialize > > * idle states suspend back-end specific data > > */ > > - for_each_possible_cpu(cpu) { > > + for_each_cpu(cpu, drv->cpumask) { > > ret = arm_cpuidle_init(cpu); > > > > /* > > @@ -157,7 +213,77 @@ out_fail: > > } > > > > cpuidle_unregister_driver(drv); > > + return ret; > > +} > > + > > +/* > > + * arm_idle_init > > + * > > + * Registers the arm specific cpuidle driver(s) with the cpuidle > > + * framework. It relies on core code to parse the idle states > > + * and initialize them using driver data structures accordingly. > > + */ > > +static int __init arm_idle_init(void) > > +{ > > + int i, ret = -ENODEV; > > + struct cpuidle_driver *drv; > > + cpumask_var_t tmpmask; > > + > > + /* > > + * These drivers require DT idle states to be present. > > + * If no idle states are detected there is no reason to > > + * proceed any further hence we return early. > > + */ > > + if (!of_find_node_by_name(NULL, "idle-states")) > > + return -ENODEV; > > + > > + if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) > > + return -ENOMEM; > > + > > + /* > > + * We need to vet idle states to create CPUidle drivers > > + * that share a common set of them. Create a tmp mask > > + * that we use to keep track of initialized cpus. > > + * Start off by initializing the mask with all possible > > + * cpus, we clear it as we go, till either all cpus > > + * have a CPUidle driver initialized or there are some > > + * CPUs that have no idle states or a parsing error > > + * occurs. > > + */ > > + cpumask_copy(tmpmask, cpu_possible_mask); > > + > > + for (i = 0; !cpumask_empty(tmpmask); i++) { > > + if (i == ARM_CPUIDLE_MAX_DRIVERS) { > > + pr_warn("number of drivers exceeding static allocation\n"); > > + break; > > + } > > + > > + drv = &arm_idle_drivers[i]; > > + drv->cpumask = kzalloc(cpumask_size(), GFP_KERNEL); > > + if (!drv->cpumask) { > > + ret = -ENOMEM; > > + break; > > + } > > + /* > > + * Force driver mask, arm_idle_init_driver() > > + * will tweak it by vetting idle states. > > + */ > > + cpumask_copy(drv->cpumask, tmpmask); > > Why do you need to copy tmpmask ? Isn't simpler to have a zero-ed > cpumask and let the arm_idle_init_driver function to set a bit instead > of clearing it ? > > > + ret = arm_idle_init_driver(drv); > > + if (ret) { > > + kfree(drv->cpumask); > > + break; > > + } > > + /* > > + * Remove the cpus that were part of the registered > > + * driver from the mask of cpus to be initialized > > + * and restart. > > + */ > > + cpumask_andnot(tmpmask, tmpmask, drv->cpumask); > > If there is a DT definition with just a cluster with the cpuidle driver > set and another one without any idle state, we will have always a > pr_warn because i == ARM_CPUIDLE_MAX_DRIVERS due to tmpmask being never > equal to a zero mask. Is it the purpose to detect such cases ? > > > + } > > > > + free_cpumask_var(tmpmask); > > return ret; > > } > > device_initcall(arm_idle_init); > > > > > -- > <http://www.linaro.org/> Linaro.org ??? Open source software for ARM SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog >
diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm index 21340e0..90c6553 100644 --- a/drivers/cpuidle/Kconfig.arm +++ b/drivers/cpuidle/Kconfig.arm @@ -3,6 +3,7 @@ # config ARM_CPUIDLE bool "Generic ARM/ARM64 CPU idle Driver" + select CPU_IDLE_MULTIPLE_DRIVERS select DT_IDLE_STATES help Select this to enable generic cpuidle driver for ARM. diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c index 545069d..251fa2a 100644 --- a/drivers/cpuidle/cpuidle-arm.c +++ b/drivers/cpuidle/cpuidle-arm.c @@ -14,6 +14,7 @@ #include <linux/cpuidle.h> #include <linux/cpumask.h> #include <linux/cpu_pm.h> +#include <linux/of_device.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of.h> @@ -58,23 +59,27 @@ static int arm_enter_idle_state(struct cpuidle_device *dev, return ret ? -1 : idx; } -static struct cpuidle_driver arm_idle_driver = { - .name = "arm_idle", - .owner = THIS_MODULE, - /* - * State at index 0 is standby wfi and considered standard - * on all ARM platforms. If in some platforms simple wfi - * can't be used as "state 0", DT bindings must be implemented - * to work around this issue and allow installing a special - * handler for idle state index 0. - */ - .states[0] = { - .enter = arm_enter_idle_state, - .exit_latency = 1, - .target_residency = 1, - .power_usage = UINT_MAX, - .name = "WFI", - .desc = "ARM WFI", +#define ARM_CPUIDLE_MAX_DRIVERS 2 + +static struct cpuidle_driver arm_idle_drivers[ARM_CPUIDLE_MAX_DRIVERS] = { + [0 ... ARM_CPUIDLE_MAX_DRIVERS - 1] = { + .name = "arm_idle", + .owner = THIS_MODULE, + /* + * State at index 0 is standby wfi and considered standard + * on all ARM platforms. If in some platforms simple wfi + * can't be used as "state 0", DT bindings must be implemented + * to work around this issue and allow installing a special + * handler for idle state index 0. + */ + .states[0] = { + .enter = arm_enter_idle_state, + .exit_latency = 1, + .target_residency = 1, + .power_usage = UINT_MAX, + .name = "WFI", + .desc = "ARM WFI", + } } }; @@ -85,17 +90,68 @@ static const struct of_device_id arm_idle_state_match[] __initconst = { }; /* - * arm_idle_init + * Compare idle states phandle properties * - * Registers the arm specific cpuidle driver with the cpuidle - * framework. It relies on core code to parse the idle states - * and initialize them using driver data structures accordingly. + * Return true if properties are valid and equal, false otherwise */ -static int __init arm_idle_init(void) +static bool __init idle_states_cmp(struct property *states1, + struct property *states2) +{ + /* + * NB: Implemented through code from drivers/of/unittest.c + * Function is generic and can be moved to generic OF code + * if needed + */ + return states1 && states2 && + (states1->length == states2->length) && + states1->value && states2->value && + !memcmp(states1->value, states2->value, states1->length); +} + +static int __init arm_idle_init_driver(struct cpuidle_driver *drv) { - int cpu, ret; - struct cpuidle_driver *drv = &arm_idle_driver; + int ret, cpu; struct cpuidle_device *dev; + struct property *curr_idle_states, *idle_states = NULL; + struct device_node *cpu_node; + + for_each_cpu(cpu, drv->cpumask) { + cpu_node = of_cpu_device_node_get(cpu); + curr_idle_states = of_find_property(cpu_node, + "cpu-idle-states", NULL); + of_node_put(cpu_node); + + /* + * Stash the first valid idle states phandle in the cpumask. + * If curr_idle_states is NULL assigning it to idle_states + * is harmless and it is managed by idle states comparison + * code. Keep track of first valid phandle so that + * subsequent cpus can compare against it. + */ + if (!idle_states) + idle_states = curr_idle_states; + + /* + * If idle states phandles are not equal, remove the + * cpu from the driver mask since a CPUidle driver + * is only capable of managing uniform idle states. + * + * Comparison works also when idle_states and + * curr_idle_states are the same property, since + * they can be == NULL so the cpu must be removed from + * the driver mask in that case too (ie cpu has no idle + * states). + */ + if (!idle_states_cmp(idle_states, curr_idle_states)) + cpumask_clear_cpu(cpu, drv->cpumask); + } + + /* + * If there are no valid states for this driver we rely on arch + * default idle behaviour, bail out + */ + if (!idle_states) + return -ENODEV; /* * Initialize idle states data, starting at index 1. @@ -117,7 +173,7 @@ static int __init arm_idle_init(void) * Call arch CPU operations in order to initialize * idle states suspend back-end specific data */ - for_each_possible_cpu(cpu) { + for_each_cpu(cpu, drv->cpumask) { ret = arm_cpuidle_init(cpu); /* @@ -157,7 +213,77 @@ out_fail: } cpuidle_unregister_driver(drv); + return ret; +} + +/* + * arm_idle_init + * + * Registers the arm specific cpuidle driver(s) with the cpuidle + * framework. It relies on core code to parse the idle states + * and initialize them using driver data structures accordingly. + */ +static int __init arm_idle_init(void) +{ + int i, ret = -ENODEV; + struct cpuidle_driver *drv; + cpumask_var_t tmpmask; + + /* + * These drivers require DT idle states to be present. + * If no idle states are detected there is no reason to + * proceed any further hence we return early. + */ + if (!of_find_node_by_name(NULL, "idle-states")) + return -ENODEV; + + if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) + return -ENOMEM; + + /* + * We need to vet idle states to create CPUidle drivers + * that share a common set of them. Create a tmp mask + * that we use to keep track of initialized cpus. + * Start off by initializing the mask with all possible + * cpus, we clear it as we go, till either all cpus + * have a CPUidle driver initialized or there are some + * CPUs that have no idle states or a parsing error + * occurs. + */ + cpumask_copy(tmpmask, cpu_possible_mask); + + for (i = 0; !cpumask_empty(tmpmask); i++) { + if (i == ARM_CPUIDLE_MAX_DRIVERS) { + pr_warn("number of drivers exceeding static allocation\n"); + break; + } + + drv = &arm_idle_drivers[i]; + drv->cpumask = kzalloc(cpumask_size(), GFP_KERNEL); + if (!drv->cpumask) { + ret = -ENOMEM; + break; + } + /* + * Force driver mask, arm_idle_init_driver() + * will tweak it by vetting idle states. + */ + cpumask_copy(drv->cpumask, tmpmask); + + ret = arm_idle_init_driver(drv); + if (ret) { + kfree(drv->cpumask); + break; + } + /* + * Remove the cpus that were part of the registered + * driver from the mask of cpus to be initialized + * and restart. + */ + cpumask_andnot(tmpmask, tmpmask, drv->cpumask); + } + free_cpumask_var(tmpmask); return ret; } device_initcall(arm_idle_init);
Some ARM systems (eg big.LITTLE ones) can be composed of CPUs having different hardware power management configurations and in the context of CPUidle, different idle states. The generic ARM CPUidle driver treats all possible CPUs as equal and initializes a common idle driver through DT idle states for all possible CPUs. Current driver cannot manage systems where CPUs are heterogeneous and therefore can have different idle states. This patch augments the generic ARM CPUidle driver, by adding code that at boot initializes CPUidle drivers by going through the cpu_possible_mask and through DT parsing detects the cpus sharing the same idle states, thus creating the CPUidle drivers cpumasks. The drivers are then initialized through the DT idle states interface, that parses and initializes the DT idle states for the cpus set in the drivers cpumasks. This patch instantiates a static array of idle drivers, some of which can turn out to be unused (eg platforms with uniform idle states on all possible CPUs), and relies on the config option CPU_IDLE_MULTIPLE_DRIVERS to be selected by default; this can cause a little memory overhead, but at the same time allows supporting most of the current and future ARM platforms through a single generic CPUidle driver. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Howard Chen <howard.chen@linaro.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Sudeep Holla <sudeep.holla@arm.com> Cc: Lina Iyer <lina.iyer@linaro.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Grant Likely <grant.likely@linaro.org> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> --- drivers/cpuidle/Kconfig.arm | 1 + drivers/cpuidle/cpuidle-arm.c | 176 ++++++++++++++++++++++++++++++++++++------ 2 files changed, 152 insertions(+), 25 deletions(-)