PM: sleep: Make async suspend handle suppliers like parents

Avoid starting "async" suspend processing upfront for devices that have
consumers and start "async" suspend processing for a device's suppliers
right after suspending the device itself.

Suggested-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://patch.msgid.link/3384525.44csPzL39Z@rjwysocki.net

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index d7ef5048a4524a0064322199b3a923c4faaf6815..04feac1a7059a3dc3a1400eac49b19331668400f 100644 (file)
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1276,10 +1276,15 @@ static bool dpm_leaf_device(struct device *dev)
                return false;
        }
 
-       return true;
+       /*
+        * Since this function is required to run under dpm_list_mtx, the
+        * list_empty() below will only return true if the device's list of
+        * consumers is actually empty before calling it.
+        */
+       return list_empty(&dev->links.consumers);
 }
 
-static void dpm_async_suspend_parent(struct device *dev, async_func_t func)
+static bool dpm_async_suspend_parent(struct device *dev, async_func_t func)
 {
        guard(mutex)(&dpm_list_mtx);
 
@@ -1291,11 +1296,31 @@ static void dpm_async_suspend_parent(struct device *dev, async_func_t func)
         * deleted before it.
         */
        if (!device_pm_initialized(dev))
-               return;
+               return false;
 
        /* Start processing the device's parent if it is "async". */
        if (dev->parent)
                dpm_async_with_cleanup(dev->parent, func);
+
+       return true;
+}
+
+static void dpm_async_suspend_superior(struct device *dev, async_func_t func)
+{
+       struct device_link *link;
+       int idx;
+
+       if (!dpm_async_suspend_parent(dev, func))
+               return;
+
+       idx = device_links_read_lock();
+
+       /* Start processing the device's "async" suppliers. */
+       list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+               if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+                       dpm_async_with_cleanup(link->supplier, func);
+
+       device_links_read_unlock(idx);
 }
 
 /**
@@ -1419,7 +1444,7 @@ Complete:
        if (error || async_error)
                return error;
 
-       dpm_async_suspend_parent(dev, async_suspend_noirq);
+       dpm_async_suspend_superior(dev, async_suspend_noirq);
 
        return 0;
 }
@@ -1615,7 +1640,7 @@ Complete:
        if (error || async_error)
                return error;
 
-       dpm_async_suspend_parent(dev, async_suspend_late);
+       dpm_async_suspend_superior(dev, async_suspend_late);
 
        return 0;
 }
@@ -1906,7 +1931,7 @@ static int device_suspend(struct device *dev, pm_message_t state, bool async)
        if (error || async_error)
                return error;
 
-       dpm_async_suspend_parent(dev, async_suspend);
+       dpm_async_suspend_superior(dev, async_suspend);
 
        return 0;
 }