linux-kernel - [PATCH RFC 01/10] PM: runtime: Add helpers to resume consumers

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Message-Id: <20250326-cross-lock-dep-v1-1-3199e49e8652@bootlin.com>
Date: Wed, 26 Mar 2025 19:26:16 +0100
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>, Pavel Machek <pavel@....cz>, 
 Len Brown <len.brown@...el.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Danilo Krummrich <dakr@...nel.org>, 
 Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-clk@...r.kernel.org, Chen-Yu Tsai <wenst@...omium.org>, 
 Lucas Stach <l.stach@...gutronix.de>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Marek Vasut <marex@...x.de>, Ulf Hansson <ulf.hansson@...aro.org>, 
 Kevin Hilman <khilman@...nel.org>, Fabio Estevam <festevam@...x.de>, 
 Jacky Bai <ping.bai@....com>, Peng Fan <peng.fan@....com>, 
 Shawn Guo <shawnguo@...nel.org>, Shengjiu Wang <shengjiu.wang@....com>, 
 linux-imx@....com, Ian Ray <ian.ray@...ealthcare.com>, 
 Hervé Codina <herve.codina@...tlin.com>, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>, 
 Saravana Kannan <saravanak@...gle.com>, 
 Miquel Raynal <miquel.raynal@...tlin.com>
Subject: [PATCH RFC 01/10] PM: runtime: Add helpers to resume consumers

The runtime PM core currently allows to runtime resume/suspend a device,
or its suppliers.

Let's make it also possible to runtime resume/suspend consumers.

Consumers and suppliers are seen here through the description made by
device_links.

Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
---
 drivers/base/power/runtime.c | 54 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pm_runtime.h   |  2 ++
 2 files changed, 56 insertions(+)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 2ee45841486bc73225b3e971164466647b3ce6d3..04bb66c18e3e4a45751fb3f9a6a1267d73757310 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1841,6 +1841,60 @@ void pm_runtime_put_suppliers(struct device *dev)
 	device_links_read_unlock(idx);
 }

+static void __pm_runtime_get_consumers(struct device *dev)
+{
+	struct device_link *link;
+
+	list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
+				device_links_read_lock_held())
+		if (link->flags & DL_FLAG_PM_RUNTIME) {
+			pm_runtime_get_sync(link->consumer);
+			__pm_runtime_get_consumers(link->consumer);
+		}
+}
+
+/**
+ * pm_runtime_get_consumers - Resume and reference-count consumer devices.
+ * @dev: Supplier device.
+ */
+void pm_runtime_get_consumers(struct device *dev)
+{
+	int idx;
+
+	idx = device_links_read_lock();
+
+	__pm_runtime_get_consumers(dev);
+
+	device_links_read_unlock(idx);
+}
+
+static void __pm_runtime_put_consumers(struct device *dev)
+{
+	struct device_link *link;
+
+	list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
+				device_links_read_lock_held())
+		if (link->flags & DL_FLAG_PM_RUNTIME) {
+			pm_runtime_put(link->consumer);
+			__pm_runtime_put_consumers(link->consumer);
+		}
+}
+
+/**
+ * pm_runtime_put_consumers - Drop references to consumer devices.
+ * @dev: Supplier device.
+ */
+void pm_runtime_put_consumers(struct device *dev)
+{
+	int idx;
+
+	idx = device_links_read_lock();
+
+	__pm_runtime_put_consumers(dev);
+
+	device_links_read_unlock(idx);
+}
+
 void pm_runtime_new_link(struct device *dev)
 {
 	spin_lock_irq(&dev->power.lock);
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index d39dc863f612fe18dc34182117f87908d63c8e6d..151c885a3f421f09509232f144618da62297d61d 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -89,6 +89,8 @@ extern u64 pm_runtime_autosuspend_expiration(struct device *dev);
 extern void pm_runtime_set_memalloc_noio(struct device *dev, bool enable);
 extern void pm_runtime_get_suppliers(struct device *dev);
 extern void pm_runtime_put_suppliers(struct device *dev);
+extern void pm_runtime_get_consumers(struct device *dev);
+extern void pm_runtime_put_consumers(struct device *dev);
 extern void pm_runtime_new_link(struct device *dev);
 extern void pm_runtime_drop_link(struct device_link *link);
 extern void pm_runtime_release_supplier(struct device_link *link);

-- 
2.48.1