linux-kernel - [PATCH] ACPI / scan: Simplify ACPI driver probing

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Message-ID: <2159292.upDGjkPUz6@vostro.rjw.lan>
Date:	Sun, 09 Jun 2013 00:28:02 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Cc:	Aaron Lu <aaron.lu@...el.com>, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] ACPI / scan: Simplify ACPI driver probing

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

There is no particular reason why acpi_bus_driver_init() needs to be
a separate function and its location with respect to its only caller,
acpi_device_probe(), makes the code a bit difficult to follow.

Besides, it doesn't really make sense to check if 'device' is not
NULL in acpi_bus_driver_init(), because we've already dereferenced
dev->driver in acpi_device_probe() at that point, so that check has
to be moved to acpi_device_probe() anyway.

For these reasons, drop acpi_bus_driver_init() altogether and move
the code from it directly into acpi_device_probe().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

Should apply on top of the bleeding-edge branch of the linux-pm.git tree.

Thanks,
Rafael

---
 drivers/acpi/scan.c |   88 +++++++++++++++++++---------------------------------
 1 file changed, 33 insertions(+), 55 deletions(-)

Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -933,32 +933,45 @@ static void acpi_device_remove_notify_ha
 					   acpi_device_notify);
 }
 
-static int acpi_bus_driver_init(struct acpi_device *, struct acpi_driver *);
 static int acpi_device_probe(struct device * dev)
 {
-	struct acpi_device *acpi_dev = to_acpi_device(dev);
-	struct acpi_driver *acpi_drv = to_acpi_driver(dev->driver);
+	struct acpi_device *acpi_dev;
+	struct acpi_driver *acpi_drv;
 	int ret;
 
-	ret = acpi_bus_driver_init(acpi_dev, acpi_drv);
-	if (!ret) {
-		if (acpi_drv->ops.notify) {
-			ret = acpi_device_install_notify_handler(acpi_dev);
-			if (ret) {
-				if (acpi_drv->ops.remove)
-					acpi_drv->ops.remove(acpi_dev);
-				acpi_dev->driver = NULL;
-				acpi_dev->driver_data = NULL;
-				return ret;
-			}
-		}
+	if (!dev || !dev->driver)
+		return -EINVAL;
+
+	acpi_dev = to_acpi_device(dev);
+	acpi_drv = to_acpi_driver(dev->driver);
+	if (!acpi_drv->ops.add)
+		return -ENOSYS;
+
+	ret = acpi_drv->ops.add(acpi_dev);
+	if (ret)
+		return ret;
+
+	acpi_dev->driver = acpi_drv;
+	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+			  "Driver [%s] successfully bound to device [%s]\n",
+			  acpi_drv->name, acpi_dev->pnp.bus_id));
 
-		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-			"Found driver [%s] for device [%s]\n",
-			acpi_drv->name, acpi_dev->pnp.bus_id));
-		get_device(dev);
+	if (acpi_drv->ops.notify) {
+		ret = acpi_device_install_notify_handler(acpi_dev);
+		if (ret) {
+			if (acpi_drv->ops.remove)
+				acpi_drv->ops.remove(acpi_dev);
+
+			acpi_dev->driver = NULL;
+			acpi_dev->driver_data = NULL;
+			return ret;
+		}
 	}
-	return ret;
+
+	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found driver [%s] for device [%s]\n",
+			  acpi_drv->name, acpi_dev->pnp.bus_id));
+	get_device(dev);
+	return 0;
 }
 
 static int acpi_device_remove(struct device * dev)
@@ -1114,41 +1127,6 @@ static void acpi_device_unregister(struc
                                  Driver Management
    -------------------------------------------------------------------------- */
 /**
- * acpi_bus_driver_init - add a device to a driver
- * @device: the device to add and initialize
- * @driver: driver for the device
- *
- * Used to initialize a device via its device driver.  Called whenever a
- * driver is bound to a device.  Invokes the driver's add() ops.
- */
-static int
-acpi_bus_driver_init(struct acpi_device *device, struct acpi_driver *driver)
-{
-	int result = 0;
-
-	if (!device || !driver)
-		return -EINVAL;
-
-	if (!driver->ops.add)
-		return -ENOSYS;
-
-	result = driver->ops.add(device);
-	if (result)
-		return result;
-
-	device->driver = driver;
-
-	/*
-	 * TBD - Configuration Management: Assign resources to device based
-	 * upon possible configuration and currently allocated resources.
-	 */
-
-	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
-			  "Driver successfully bound to device\n"));
-	return 0;
-}
-
-/**
  * acpi_bus_register_driver - register a driver with the ACPI bus
  * @driver: driver being registered
  *

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