lib: psci: early suspend handler for platforms
This patch adds an early suspend handler, that executes with
SMP and data cache enabled. This handler allows platforms to
perform any early actions during the CPU suspend entry sequence.
This handler is optional and platforms can choose to implement it
depending on their needs. The `pwr_domain_suspend` handler still
exists and platforms can keep on using it without any side effects.
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
diff --git a/docs/porting-guide.rst b/docs/porting-guide.rst
index 4d4cdcd..bf8dea7 100644
--- a/docs/porting-guide.rst
+++ b/docs/porting-guide.rst
@@ -2060,6 +2060,23 @@
for the higher power domain levels depending on the result of state
coordination. The generic code expects the handler to succeed.
+plat\_psci\_ops.pwr\_domain\_suspend\_pwrdown\_early() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This optional function may be used as a performance optimization to replace
+or complement pwr_domain_suspend() on some platforms. Its calling semantics
+are identical to pwr_domain_suspend(), except the PSCI implementation only
+calls this function when suspending to a power down state, and it guarantees
+that data caches are enabled.
+
+When HW_ASSISTED_COHERENCY = 0, the PSCI implementation disables data caches
+before calling pwr_domain_suspend(). If the target_state corresponds to a
+power down state and it is safe to perform some or all of the platform
+specific actions in that function with data caches enabled, it may be more
+efficient to move those actions to this function. When HW_ASSISTED_COHERENCY
+= 1, data caches remain enabled throughout, and so there is no advantage to
+moving platform specific actions to this function.
+
plat\_psci\_ops.pwr\_domain\_suspend()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~