linux-kernel - [PATCH 05/16] bus: simple-pm-bus: Populate child nodes at probe

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Message-ID: <20250407145546.270683-6-herve.codina@bootlin.com>
Date: Mon,  7 Apr 2025 16:55:34 +0200
From: Herve Codina <herve.codina@...tlin.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Andi Shyti <andi.shyti@...nel.org>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Peter Rosin <peda@...ntia.se>,
	Derek Kiernan <derek.kiernan@....com>,
	Dragan Cvetic <dragan.cvetic@....com>,
	Arnd Bergmann <arnd@...db.de>,
	Herve Codina <herve.codina@...tlin.com>,
	Rob Herring <robh@...nel.org>,
	Saravana Kannan <saravanak@...gle.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Mark Brown <broonie@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Daniel Scally <djrscally@...il.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Wolfram Sang <wsa@...nel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-clk@...r.kernel.org,
	linux-i2c@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-pci@...r.kernel.org,
	linux-spi@...r.kernel.org,
	linux-acpi@...r.kernel.org,
	Allan Nielsen <allan.nielsen@...rochip.com>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	Steen Hegelund <steen.hegelund@...rochip.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: [PATCH 05/16] bus: simple-pm-bus: Populate child nodes at probe

The simple-pm-bus drivers handles several simple bus. When it is used
with busses other than a compatible "simple-pm-bus", it don't populate
its child devices during its probe.

This confuses fw_devlink and results in wrong or missing devlinks.

Once a driver is bound to a device and the probe() has been called,
device_links_driver_bound() is called.

This function performs operation based on the following assumption:
    If a child firmware node of the bound device is not added as a
    device, it will never be added.

Among operations done on fw_devlinks of those "never be added" devices,
device_links_driver_bound() changes their supplier.

With devices attached to a simple-bus compatible device, this change
leads to wrong devlinks where supplier of devices points to the device
parent (i.e. simple-bus compatible device) instead of the device itself
(i.e. simple-bus child).

When the device attached to the simple-bus is removed, because devlinks
are not correct, its consumers are not removed first.

In order to have correct devlinks created, make the simple-pm-bus driver
compliant with the devlink assumption and create its child devices
during its probe.

Signed-off-by: Herve Codina <herve.codina@...tlin.com>
---
 drivers/bus/simple-pm-bus.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c
index d8e029e7e53f..93c6ba605d7a 100644
--- a/drivers/bus/simple-pm-bus.c
+++ b/drivers/bus/simple-pm-bus.c
@@ -42,14 +42,14 @@ static int simple_pm_bus_probe(struct platform_device *pdev)
 	match = of_match_device(dev->driver->of_match_table, dev);
 	/*
 	 * These are transparent bus devices (not simple-pm-bus matches) that
-	 * have their child nodes populated automatically.  So, don't need to
-	 * do anything more. We only match with the device if this driver is
-	 * the most specific match because we don't want to incorrectly bind to
-	 * a device that has a more specific driver.
+	 * have their child nodes populated automatically. So, don't need to
+	 * do anything more except populate child nodes. We only match with the
+	 * device if this driver is the most specific match because we don't
+	 * want to incorrectly bind to a device that has a more specific driver.
 	 */
 	if (match && match->data) {
 		if (of_property_match_string(np, "compatible", match->compatible) == 0)
-			return 0;
+			goto populate;
 		else
 			return -ENODEV;
 	}
@@ -64,13 +64,14 @@ static int simple_pm_bus_probe(struct platform_device *pdev)
 
 	dev_set_drvdata(&pdev->dev, bus);
 
-	dev_dbg(&pdev->dev, "%s\n", __func__);
-
 	pm_runtime_enable(&pdev->dev);
 
+populate:
 	if (np)
 		of_platform_populate(np, NULL, lookup, &pdev->dev);
 
+	dev_dbg(&pdev->dev, "%s\n", __func__);
+
 	return 0;
 }
 
@@ -78,12 +79,16 @@ static void simple_pm_bus_remove(struct platform_device *pdev)
 {
 	const void *data = of_device_get_match_data(&pdev->dev);
 
-	if (pdev->driver_override || data)
+	if (pdev->driver_override)
 		return;
 
 	dev_dbg(&pdev->dev, "%s\n", __func__);
 
-	pm_runtime_disable(&pdev->dev);
+	if (pdev->dev.of_node)
+		of_platform_depopulate(&pdev->dev);
+
+	if (!data)
+		pm_runtime_disable(&pdev->dev);
 }
 
 static int simple_pm_bus_runtime_suspend(struct device *dev)
-- 
2.49.0