Re: [PATCH v2] cpuidle: Do not use CPUIDLE_DRIVER_STATE_START in cpuidle.c
On 05/28/2015 07:39 AM, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > The CPUIDLE_DRIVER_STATE_START symbol is defined as 1 only if > CONFIG_ARCH_HAS_CPU_RELAX is set, otherwise it is defined as 0. > However, if CONFIG_ARCH_HAS_CPU_RELAX is set, the first (index 0) > entry in the cpuidle driver's table of states is overwritten with > the default "poll" entry by the core. The "state" defined by the > "poll" entry doesn't provide ->enter_dead and ->enter_freeze > callbacks and its exit_latency is 0. > > For this reason, it is not necessary to use CPUIDLE_DRIVER_STATE_START > in cpuidle_play_dead() (->enter_dead is NULL, so the "poll state" > will be skipped by the loop). > > It also is arguably unuseful to return states with exit_latency > equal to 0 from find_deepest_state(), so the function can be modified > to start the loop from index 0 and the "poll state" will be skipped by > it as a result of the check against latency_req. > > Signed-off-by: Rafael J. Wysocki > --- > drivers/cpuidle/cpuidle.c |6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > Index: linux-pm/drivers/cpuidle/cpuidle.c > === > --- linux-pm.orig/drivers/cpuidle/cpuidle.c > +++ linux-pm/drivers/cpuidle/cpuidle.c > @@ -65,7 +65,7 @@ int cpuidle_play_dead(void) > return -ENODEV; > > /* Find lowest-power state that supports long-term idle */ > - for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--) > + for (i = drv->state_count - 1; i >= 0; i--) > if (drv->states[i].enter_dead) > return drv->states[i].enter_dead(dev, i); > > @@ -79,9 +79,9 @@ static int find_deepest_state(struct cpu > bool freeze) > { > unsigned int latency_req = 0; > - int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1; > + int i, ret = -ENXIO; > > - for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) { > + for (i = 0; i < drv->state_count; i++) { > struct cpuidle_state *s = >states[i]; > struct cpuidle_state_usage *su = >states_usage[i]; > Reviewed-by: Preeti U Murthy > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v2] cpuidle: Do not use CPUIDLE_DRIVER_STATE_START in cpuidle.c
From: Rafael J. Wysocki The CPUIDLE_DRIVER_STATE_START symbol is defined as 1 only if CONFIG_ARCH_HAS_CPU_RELAX is set, otherwise it is defined as 0. However, if CONFIG_ARCH_HAS_CPU_RELAX is set, the first (index 0) entry in the cpuidle driver's table of states is overwritten with the default "poll" entry by the core. The "state" defined by the "poll" entry doesn't provide ->enter_dead and ->enter_freeze callbacks and its exit_latency is 0. For this reason, it is not necessary to use CPUIDLE_DRIVER_STATE_START in cpuidle_play_dead() (->enter_dead is NULL, so the "poll state" will be skipped by the loop). It also is arguably unuseful to return states with exit_latency equal to 0 from find_deepest_state(), so the function can be modified to start the loop from index 0 and the "poll state" will be skipped by it as a result of the check against latency_req. Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/cpuidle.c |6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) Index: linux-pm/drivers/cpuidle/cpuidle.c === --- linux-pm.orig/drivers/cpuidle/cpuidle.c +++ linux-pm/drivers/cpuidle/cpuidle.c @@ -65,7 +65,7 @@ int cpuidle_play_dead(void) return -ENODEV; /* Find lowest-power state that supports long-term idle */ - for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--) + for (i = drv->state_count - 1; i >= 0; i--) if (drv->states[i].enter_dead) return drv->states[i].enter_dead(dev, i); @@ -79,9 +79,9 @@ static int find_deepest_state(struct cpu bool freeze) { unsigned int latency_req = 0; - int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1; + int i, ret = -ENXIO; - for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) { + for (i = 0; i < drv->state_count; i++) { struct cpuidle_state *s = >states[i]; struct cpuidle_state_usage *su = >states_usage[i]; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2] cpuidle: Do not use CPUIDLE_DRIVER_STATE_START in cpuidle.c
On 05/28/2015 07:39 AM, Rafael J. Wysocki wrote: From: Rafael J. Wysocki rafael.j.wyso...@intel.com The CPUIDLE_DRIVER_STATE_START symbol is defined as 1 only if CONFIG_ARCH_HAS_CPU_RELAX is set, otherwise it is defined as 0. However, if CONFIG_ARCH_HAS_CPU_RELAX is set, the first (index 0) entry in the cpuidle driver's table of states is overwritten with the default poll entry by the core. The state defined by the poll entry doesn't provide -enter_dead and -enter_freeze callbacks and its exit_latency is 0. For this reason, it is not necessary to use CPUIDLE_DRIVER_STATE_START in cpuidle_play_dead() (-enter_dead is NULL, so the poll state will be skipped by the loop). It also is arguably unuseful to return states with exit_latency equal to 0 from find_deepest_state(), so the function can be modified to start the loop from index 0 and the poll state will be skipped by it as a result of the check against latency_req. Signed-off-by: Rafael J. Wysocki rafael.j.wyso...@intel.com --- drivers/cpuidle/cpuidle.c |6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) Index: linux-pm/drivers/cpuidle/cpuidle.c === --- linux-pm.orig/drivers/cpuidle/cpuidle.c +++ linux-pm/drivers/cpuidle/cpuidle.c @@ -65,7 +65,7 @@ int cpuidle_play_dead(void) return -ENODEV; /* Find lowest-power state that supports long-term idle */ - for (i = drv-state_count - 1; i = CPUIDLE_DRIVER_STATE_START; i--) + for (i = drv-state_count - 1; i = 0; i--) if (drv-states[i].enter_dead) return drv-states[i].enter_dead(dev, i); @@ -79,9 +79,9 @@ static int find_deepest_state(struct cpu bool freeze) { unsigned int latency_req = 0; - int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1; + int i, ret = -ENXIO; - for (i = CPUIDLE_DRIVER_STATE_START; i drv-state_count; i++) { + for (i = 0; i drv-state_count; i++) { struct cpuidle_state *s = drv-states[i]; struct cpuidle_state_usage *su = dev-states_usage[i]; Reviewed-by: Preeti U Murthy pre...@linux.vnet.ibm.com -- To unsubscribe from this list: send the line unsubscribe linux-pm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v2] cpuidle: Do not use CPUIDLE_DRIVER_STATE_START in cpuidle.c
From: Rafael J. Wysocki rafael.j.wyso...@intel.com The CPUIDLE_DRIVER_STATE_START symbol is defined as 1 only if CONFIG_ARCH_HAS_CPU_RELAX is set, otherwise it is defined as 0. However, if CONFIG_ARCH_HAS_CPU_RELAX is set, the first (index 0) entry in the cpuidle driver's table of states is overwritten with the default poll entry by the core. The state defined by the poll entry doesn't provide -enter_dead and -enter_freeze callbacks and its exit_latency is 0. For this reason, it is not necessary to use CPUIDLE_DRIVER_STATE_START in cpuidle_play_dead() (-enter_dead is NULL, so the poll state will be skipped by the loop). It also is arguably unuseful to return states with exit_latency equal to 0 from find_deepest_state(), so the function can be modified to start the loop from index 0 and the poll state will be skipped by it as a result of the check against latency_req. Signed-off-by: Rafael J. Wysocki rafael.j.wyso...@intel.com --- drivers/cpuidle/cpuidle.c |6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) Index: linux-pm/drivers/cpuidle/cpuidle.c === --- linux-pm.orig/drivers/cpuidle/cpuidle.c +++ linux-pm/drivers/cpuidle/cpuidle.c @@ -65,7 +65,7 @@ int cpuidle_play_dead(void) return -ENODEV; /* Find lowest-power state that supports long-term idle */ - for (i = drv-state_count - 1; i = CPUIDLE_DRIVER_STATE_START; i--) + for (i = drv-state_count - 1; i = 0; i--) if (drv-states[i].enter_dead) return drv-states[i].enter_dead(dev, i); @@ -79,9 +79,9 @@ static int find_deepest_state(struct cpu bool freeze) { unsigned int latency_req = 0; - int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1; + int i, ret = -ENXIO; - for (i = CPUIDLE_DRIVER_STATE_START; i drv-state_count; i++) { + for (i = 0; i drv-state_count; i++) { struct cpuidle_state *s = drv-states[i]; struct cpuidle_state_usage *su = dev-states_usage[i]; -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/