linux-kernel - [PATCH v1] i3c: master: Enable runtime PM for master controller

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Message-Id: <20240228093407.4038399-1-quic_msavaliy@quicinc.com>
Date: Wed, 28 Feb 2024 15:04:07 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: alexandre.belloni@...tlin.com, linux-i3c@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc: andersson@...nel.org, vkoul@...nel.org, manivannan.sadhasivam@...aro.org,
        Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
Subject: [PATCH v1] i3c: master: Enable runtime PM for master controller

Enable runtime PM for i3c master node during master registration time.

Sometimes i3c client device driver may want to control the PM of the
parent (master) to perform the transactions and save the power in an
efficient way by controlling the session. Hence device can call PM
APIs by passing the parent node.

Here, I3C target device when calls pm_runtime_get_sync(dev->parent)
couldn't invoke master drivers runtime PM callback registered by
the master driver because parent's PM status was disabled in the
Master node.

Also call pm_runtime_no_callbacks() and pm_suspend_ignore_children()
for the master node to not have any callback addition and ignore the
children to have runtime PM work just locally in the driver. This
should be generic and common change for all i3c devices and should
not have any other impact.

With these changes, I3C client device works and able to invoke
master driver registered runtime PM callbacks.

Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
---
 drivers/i3c/master.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 3afa530c5e32..a3dc88974f92 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -13,6 +13,7 @@
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/of.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>
@@ -2812,6 +2813,10 @@ int i3c_master_register(struct i3c_master_controller *master,

 	i3c_bus_notify(i3cbus, I3C_NOTIFY_BUS_ADD);

+	pm_runtime_no_callbacks(&master->dev);
+	pm_suspend_ignore_children(&master->dev, true);
+	pm_runtime_enable(&master->dev);
+
 	/*
 	 * We're done initializing the bus and the controller, we can now
 	 * register I3C devices discovered during the initial DAA.
@@ -2849,6 +2854,7 @@ void i3c_master_unregister(struct i3c_master_controller *master)
 	i3c_master_i2c_adapter_cleanup(master);
 	i3c_master_unregister_i3c_devs(master);
 	i3c_master_bus_cleanup(master);
+	pm_runtime_disable(&master->dev);
 	device_unregister(&master->dev);
 }
 EXPORT_SYMBOL_GPL(i3c_master_unregister);
-- 
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