driver-core: remove lock for platform devices during probe

During driver probe procedure, lock on the parent of
platform devices could be removed to make probe in parallel.

Change-Id: I5457869e056a55b51dd91937d6202947b13977eb
Signed-off-by: vkakani <vkakani@codeaurora.org>
Signed-off-by: Wei Li <weili@codeaurora.org>

Makefile

@@ -404,7 +404,9 @@ KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		   -Wno-format-security \
 		   -std=gnu89 $(call cc-option,-fno-PIE)
 
-
+ifeq ($(TARGET_BOARD_TYPE),auto)
+KBUILD_CFLAGS    += -DCONFIG_PLATFORM_AUTO
+endif
 KBUILD_AFLAGS_KERNEL :=
 KBUILD_CFLAGS_KERNEL :=
 KBUILD_AFLAGS   := -D__ASSEMBLY__ $(call cc-option,-fno-PIE)

drivers/base/dd.c

@@ -25,6 +25,7 @@
 #include <linux/async.h>
 #include <linux/pm_runtime.h>
 #include <linux/pinctrl/devinfo.h>
+#include <linux/platform_device.h>
 
 #include "base.h"
 #include "power/power.h"
@@ -642,6 +643,20 @@ void device_initial_probe(struct device *dev)
 {
 	__device_attach(dev, true);
 }
+#ifdef CONFIG_PLATFORM_AUTO
+static inline int lock_parent(struct device *dev)
+{
+	if (!dev->parent || dev->bus == &platform_bus_type)
+		return 0;
+
+	return 1;
+}
+#else
+static inline int lock_parent(struct device *dev)
+{
+	return dev->parent ? 1 : 0;
+}
+#endif
 
 static int __driver_attach(struct device *dev, void *data)
 {
@@ -659,14 +674,13 @@ static int __driver_attach(struct device *dev, void *data)
 
 	if (!driver_match_device(drv, dev))
 		return 0;
-
+	if (lock_parent(dev))
-	if (dev->parent)	/* Needed for USB */
 		device_lock(dev->parent);
 	device_lock(dev);
 	if (!dev->driver)
 		driver_probe_device(drv, dev);
 	device_unlock(dev);
-	if (dev->parent)
+	if (lock_parent(dev))
 		device_unlock(dev->parent);
 
 	return 0;