Return success if an interrupt is seen during PSCI CPU_SUSPEND

This patch adds support to return SUCCESS if a pending interrupt is
detected during a CPU_SUSPEND call to a power down state. The check
is performed as late as possible without losing the ability to return
to the caller. This reduces the overhead incurred by a CPU in
undergoing a complete power cycle when a wakeup interrupt is already
pending.

Fixes ARM-Software/tf-issues#102

Change-Id: I1aff04a74b704a2f529734428030d1d10750fd4b

diff --git a/include/lib/aarch64/arch_helpers.h b/include/lib/aarch64/arch_helpers.h
index 7d24a5378351d60b8fe0f5bbe91e4d7de5964585..65941e6cfc9b0aee45870760ddcd55075e4eacd0 100644 (file)
--- a/include/lib/aarch64/arch_helpers.h
+++ b/include/lib/aarch64/arch_helpers.h
@@ -270,6 +270,8 @@ DEFINE_SYSREG_RW_FUNCS(cntvoff_el2)
 DEFINE_SYSREG_RW_FUNCS(vpidr_el2)
 DEFINE_SYSREG_RW_FUNCS(vmpidr_el2)
 
+DEFINE_SYSREG_READ_FUNC(isr_el1)
+
 /* GICv3 System Registers */
 
 DEFINE_RENAME_SYSREG_RW_FUNCS(icc_sre_el1, ICC_SRE_EL1)

diff --git a/services/std_svc/psci/psci_afflvl_off.c b/services/std_svc/psci/psci_afflvl_off.c
index d1b7e88d72e8dd366bc6015af01b44ad45d3c966..ceb51f83e9d37ac31144111ac40295ede3dc8cbf 100644 (file)
--- a/services/std_svc/psci/psci_afflvl_off.c
+++ b/services/std_svc/psci/psci_afflvl_off.c
@@ -236,5 +236,13 @@ exit:
                                  end_afflvl,
                                  mpidr_nodes);
 
+       /*
+        * Check if all actions needed to safely power down this cpu have
+        * successfully completed. Enter a wfi loop which will allow the
+        * power controller to physically power down this cpu.
+        */
+       if (rc == PSCI_E_SUCCESS)
+               psci_power_down_wfi();
+
        return rc;
 }

diff --git a/services/std_svc/psci/psci_afflvl_suspend.c b/services/std_svc/psci/psci_afflvl_suspend.c
index 35f9e4a5a42d36047948a18de836b456cfd6db88..9ede65d015126b4113e475ea59ad4b591e4fba46 100644 (file)
--- a/services/std_svc/psci/psci_afflvl_suspend.c
+++ b/services/std_svc/psci/psci_afflvl_suspend.c
@@ -257,6 +257,7 @@ void psci_afflvl_suspend(entry_point_info_t *ep,
                        int start_afflvl,
                        int end_afflvl)
 {
+       int skip_wfi = 0;
        mpidr_aff_map_nodes_t mpidr_nodes;
        unsigned int max_phys_off_afflvl;
 
@@ -280,6 +281,16 @@ void psci_afflvl_suspend(entry_point_info_t *ep,
                                  end_afflvl,
                                  mpidr_nodes);
 
+       /*
+        * We check if there are any pending interrupts after the delay
+        * introduced by lock contention to increase the chances of early
+        * detection that a wake-up interrupt has fired.
+        */
+       if (read_isr_el1()) {
+               skip_wfi = 1;
+               goto exit;
+       }
+
        /*
         * Call the cpu suspend handler registered by the Secure Payload
         * Dispatcher to let it do any bookeeping. If the handler encounters an
@@ -323,6 +334,7 @@ void psci_afflvl_suspend(entry_point_info_t *ep,
         */
        psci_set_max_phys_off_afflvl(PSCI_INVALID_DATA);
 
+exit:
        /*
         * Release the locks corresponding to each affinity level in the
         * reverse order to which they were acquired.
@@ -330,6 +342,8 @@ void psci_afflvl_suspend(entry_point_info_t *ep,
        psci_release_afflvl_locks(start_afflvl,
                                  end_afflvl,
                                  mpidr_nodes);
+       if (!skip_wfi)
+               psci_power_down_wfi();
 }
 
 /*******************************************************************************

diff --git a/services/std_svc/psci/psci_main.c b/services/std_svc/psci/psci_main.c
index 7c686949f73c143998dd7f9e2fbddc4d8281d654..91d16f46a91c62804b07c1900672c8f4c4880e2a 100644 (file)
--- a/services/std_svc/psci/psci_main.c
+++ b/services/std_svc/psci/psci_main.c
@@ -161,8 +161,6 @@ int psci_cpu_suspend(unsigned int power_state,
                            MPIDR_AFFLVL0,
                            target_afflvl);
 
-       psci_power_down_wfi();
-
        /* Reset PSCI power state parameter for the core. */
        psci_set_suspend_power_state(PSCI_INVALID_DATA);
        return PSCI_E_SUCCESS;
@@ -181,14 +179,6 @@ int psci_cpu_off(void)
         */
        rc = psci_afflvl_off(MPIDR_AFFLVL0, target_afflvl);
 
-       /*
-        * Check if all actions needed to safely power down this cpu have
-        * successfully completed. Enter a wfi loop which will allow the
-        * power controller to physically power down this cpu.
-        */
-       if (rc == PSCI_E_SUCCESS)
-               psci_power_down_wfi();
-
        /*
         * The only error cpu_off can return is E_DENIED. So check if that's
         * indeed the case.