linux-kernel - [PATCH v2 2/2] drivers: bus: simple-pm-bus: Add support for probing simple bus only devices

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Date:   Thu,  2 Sep 2021 16:04:41 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     Saravana Kannan <saravanak@...gle.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        kernel-team@...roid.com, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: [PATCH v2 2/2] drivers: bus: simple-pm-bus: Add support for probing
 simple bus only devices

The OF platform code sets up simple bus only devices (i.e. devices that
won't match with any other driver) to get probed by the simple-pm-bus to
keep fw_devlink from blocking probe() or sync_state() [1] callbacks of
other devices. There's no need to populate the child devices since the
OF platform code would do that anyway, so return early for these simple
bus only devices.

[1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@mail.gmail.com/
Signed-off-by: Saravana Kannan <saravanak@...gle.com>
Tested-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/bus/simple-pm-bus.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c
index 01a3d0cd08ed..91d52021b7f9 100644
--- a/drivers/bus/simple-pm-bus.c
+++ b/drivers/bus/simple-pm-bus.c
@@ -19,6 +19,13 @@ static int simple_pm_bus_probe(struct platform_device *pdev)
 	const struct of_dev_auxdata *lookup = dev_get_platdata(&pdev->dev);
 	struct device_node *np = pdev->dev.of_node;
 
+	/*
+	 * These are transparent bus devices (not simple-pm-bus matches) that
+	 * get populated automatically.  So, don't need to do anything more.
+	 */
+	if (pdev->driver_override)
+		return 0;
+
 	dev_dbg(&pdev->dev, "%s\n", __func__);
 
 	pm_runtime_enable(&pdev->dev);
-- 
2.33.0.153.gba50c8fa24-goog