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Fix use of stale power states in PSCI standby finisher 

A PSCI CPU_SUSPEND request to place a CPU in retention states at power levels
higher than the CPU power level is subject to the same state coordination as a
power down state. A CPU could implement multiple retention states at a
particular power level. When exiting WFI, the non-CPU power levels may be in a
different retention state to what was initially requested, therefore each CPU
should refresh its view of the states of all power levels.

Previously, a CPU re-used the state of the power levels when it entered the
retention state. This patch fixes this issue by ensuring that a CPU upon exit
from retention reads the state of each power level afresh.

Change-Id: I93b5f5065c63400c6fd2598dbaafac385748f989
This commit is contained in:
Achin Gupta 2016-06-28 16:46:15 +01:00
parent 3dd9835f8a
commit 61eae524b6
3 changed files with 15 additions and 5 deletions
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4
lib/psci/psci_common.c
View File

@ -252,8 +252,8 @@ static plat_local_state_t *psci_get_req_local_pwr_states(unsigned int pwrlvl,
* function will be called after a cpu is powered on to find the local state
* each power domain has emerged from.
*****************************************************************************/
static void psci_get_target_local_pwr_states(unsigned int end_pwrlvl,
psci_power_state_t *target_state)
void psci_get_target_local_pwr_states(unsigned int end_pwrlvl,
psci_power_state_t *target_state)
{
unsigned int parent_idx, lvl;
plat_local_state_t *pd_state = target_state->pwr_domain_state;

2
lib/psci/psci_private.h
View File

@ -192,6 +192,8 @@ int psci_validate_power_state(unsigned int power_state,
void psci_query_sys_suspend_pwrstate(psci_power_state_t *state_info);
int psci_validate_mpidr(u_register_t mpidr);
void psci_init_req_local_pwr_states(void);
void psci_get_target_local_pwr_states(unsigned int end_pwrlvl,
psci_power_state_t *target_state);
int psci_validate_entry_point(entry_point_info_t *ep,
uintptr_t entrypoint, u_register_t context_id);
void psci_get_parent_pwr_domain_nodes(unsigned int cpu_idx,

14
lib/psci/psci_suspend.c
View File

@ -45,17 +45,25 @@
* from standby/retention states at multiple power levels.
******************************************************************************/
static void psci_suspend_to_standby_finisher(unsigned int cpu_idx,
psci_power_state_t *state_info,
unsigned int end_pwrlvl)
{
psci_power_state_t state_info;
psci_acquire_pwr_domain_locks(end_pwrlvl,
cpu_idx);
/*
* Find out which retention states this CPU has exited from until the
* 'end_pwrlvl'. The exit retention state could be deeper than the entry
* state as a result of state coordination amongst other CPUs post wfi.
*/
psci_get_target_local_pwr_states(end_pwrlvl, &state_info);
/*
* Plat. management: Allow the platform to do operations
* on waking up from retention.
*/
psci_plat_pm_ops->pwr_domain_suspend_finish(state_info);
psci_plat_pm_ops->pwr_domain_suspend_finish(&state_info);
/*
* Set the requested and target state of this CPU and all the higher
@ -222,7 +230,7 @@ exit:
* After we wake up from context retaining suspend, call the
* context retaining suspend finisher.
*/
psci_suspend_to_standby_finisher(idx, state_info, end_pwrlvl);
psci_suspend_to_standby_finisher(idx, end_pwrlvl);
}
/*******************************************************************************