PSCI: Lookup list of parent nodes to lock only once
When acquiring or releasing the power domain locks for a given CPU the
parent nodes are looked up by walking the up the PD tree list on both the
acquire and release path, only one set of lookups is needed. Fetch the
parent nodes first and pass this list into both the acquire and release
functions to avoid the double lookup.
This also allows us to not have to do this lookup after coherency has
been exited during the core power down sequence. The shared struct
psci_cpu_pd_nodes is not placed in coherent memory like is done
for psci_non_cpu_pd_nodes and doing so would negatively affect
performance. With this patch we remove the need to have it in coherent
memory by moving the access out of psci_release_pwr_domain_locks().
Signed-off-by: Andrew F. Davis <afd@ti.com>
Change-Id: I7b9cfa9d31148dea0f5e21091c8b45ef7fe4c4ab
diff --git a/lib/psci/psci_off.c b/lib/psci/psci_off.c
index ac03e05..e8cd8fe 100644
--- a/lib/psci/psci_off.c
+++ b/lib/psci/psci_off.c
@@ -45,6 +45,7 @@
int rc = PSCI_E_SUCCESS;
int idx = (int) plat_my_core_pos();
psci_power_state_t state_info;
+ unsigned int parent_nodes[PLAT_MAX_PWR_LVL] = {0};
/*
* This function must only be called on platforms where the
@@ -56,11 +57,20 @@
psci_set_power_off_state(&state_info);
/*
+ * Get the parent nodes here, this is important to do before we
+ * initiate the power down sequence as after that point the core may
+ * have exited coherency and its cache may be disabled, any access to
+ * shared memory after that (such as the parent node lookup in
+ * psci_cpu_pd_nodes) can cause coherency issues on some platforms.
+ */
+ psci_get_parent_pwr_domain_nodes(idx, end_pwrlvl, parent_nodes);
+
+ /*
* This function acquires the lock corresponding to each power
* level so that by the time all locks are taken, the system topology
* is snapshot and state management can be done safely.
*/
- psci_acquire_pwr_domain_locks(end_pwrlvl, idx);
+ psci_acquire_pwr_domain_locks(end_pwrlvl, parent_nodes);
/*
* Call the cpu off handler registered by the Secure Payload Dispatcher
@@ -122,7 +132,7 @@
* Release the locks corresponding to each power level in the
* reverse order to which they were acquired.
*/
- psci_release_pwr_domain_locks(end_pwrlvl, idx);
+ psci_release_pwr_domain_locks(end_pwrlvl, parent_nodes);
/*
* Check if all actions needed to safely power down this cpu have