video: tegra: dc: disuse notifier

Due to issues with rcu notifiers on secureos, modifying dc flip
notifications to use a simple callback instead.

Bug 1028850

Change-Id: Iebf2a6d64d7316e3df2b88444201f9f9a29698c5
Signed-off-by: Ilan Aelion <iaelion@nvidia.com>
Reviewed-on: http://git-master/r/123103
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Jon Mayo <jmayo@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: Nitin Kumbhar <nkumbhar@nvidia.com>

3 files changed, 41 insertions, 46 deletions

diff --git a/arch/arm/mach-tegra/include/mach/dc.h b/arch/arm/mach-tegra/include/mach/dc.h
index 47210c1cd87b..b60a913ff083 100644
--- a/arch/arm/mach-tegra/include/mach/dc.h
+++ b/arch/arm/mach-tegra/include/mach/dc.h
@@ -25,7 +25,6 @@
 #include <linux/pm.h>
 #include <linux/types.h>
 #include <drm/drm_fixed.h>
-#include <linux/notifier.h>
 
 #define TEGRA_MAX_DC		2
 #define DC_N_WINDOWS		3
@@ -585,8 +584,8 @@ struct tegra_dc_edid {
 struct tegra_dc_edid *tegra_dc_get_edid(struct tegra_dc *dc);
 void tegra_dc_put_edid(struct tegra_dc_edid *edid);
 
-int tegra_dc_register_flip_notifier(struct notifier_block *nb);
-int tegra_dc_unregister_flip_notifier(struct notifier_block *nb);
+int tegra_dc_set_flip_callback(void (*callback)(void));
+int tegra_dc_unset_flip_callback(void);
 int tegra_dc_get_panel_sync_rate(void);
 
 #endif
diff --git a/drivers/misc/tegra-throughput.c b/drivers/misc/tegra-throughput.c
index 26573d8afc1a..366b0ecc10e6 100644
--- a/drivers/misc/tegra-throughput.c
+++ b/drivers/misc/tegra-throughput.c
@@ -19,7 +19,6 @@
 
 #include <linux/kthread.h>
 #include <linux/ktime.h>
-#include <linux/notifier.h>
 #include <linux/miscdevice.h>
 #include <linux/fs.h>
 #include <linux/init.h>
@@ -45,12 +44,10 @@ static void set_throughput_hint(struct work_struct *work)
 	nvhost_scale3d_set_throughput_hint(throughput_hint);
 }
 
-static int throughput_flip_notifier(struct notifier_block *nb,
-					     unsigned long val,
-					     void *data)
+static int throughput_flip_callback(void)
 {
-	/* only register flips when a single display is active */
-	if (val != 1 || multiple_app_disable)
+	/* only register flips when a single app is active */
+	if (multiple_app_disable)
 		return NOTIFY_DONE;
 	else {
 		long timediff;
@@ -65,7 +62,7 @@ static int throughput_flip_notifier(struct notifier_block *nb,
 				last_frame_time = (unsigned short) timediff;
 
 			if (last_frame_time == 0) {
-				pr_warn("%s: notifications %lld nsec apart\n",
+				pr_warn("%s: flips %lld nsec apart\n",
 					__func__, now.tv64 - last_flip.tv64);
 				return NOTIFY_DONE;
 			}
@@ -82,10 +79,6 @@ static int throughput_flip_notifier(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
-static struct notifier_block throughput_flip_nb = {
-	.notifier_call = throughput_flip_notifier,
-};
-
 static int sync_rate;
 static int throughput_active_app_count;
 
@@ -104,17 +97,15 @@ static void reset_target_frame_time(void)
 		__func__, sync_rate, target_frame_time);
 }
 
-static int notifier_initialized;
+static int callback_initialized;
 
 static int throughput_open(struct inode *inode, struct file *file)
 {
-	int need_init = 0;
-
 	spin_lock(&lock);
 
-	if (!notifier_initialized) {
-		notifier_initialized = 1;
-		need_init = 1;
+	if (!callback_initialized) {
+		callback_initialized = 1;
+		tegra_dc_set_flip_callback(throughput_flip_callback);
 	}
 
 	throughput_active_app_count++;
@@ -123,8 +114,6 @@ static int throughput_open(struct inode *inode, struct file *file)
 
 	spin_unlock(&lock);
 
-	if (need_init)
-		tegra_dc_register_flip_notifier(&throughput_flip_nb);
 
 	pr_debug("throughput_open node %p file %p\n", inode, file);
 
@@ -133,23 +122,18 @@ static int throughput_open(struct inode *inode, struct file *file)
 
 static int throughput_release(struct inode *inode, struct file *file)
 {
-	int need_deinit = 0;
-
 	spin_lock(&lock);
 
 	throughput_active_app_count--;
 	if (throughput_active_app_count == 0) {
 		reset_target_frame_time();
 		multiple_app_disable = 0;
-		notifier_initialized = 0;
-		need_deinit = 1;
+		callback_initialized = 0;
+		tegra_dc_unset_flip_callback();
 	}
 
 	spin_unlock(&lock);
 
-	if (need_deinit)
-		tegra_dc_unregister_flip_notifier(&throughput_flip_nb);
-
 	pr_debug("throughput_release node %p file %p\n", inode, file);
 
 	return 0;
diff --git a/drivers/video/tegra/dc/ext/dev.c b/drivers/video/tegra/dc/ext/dev.c
index 92e42ce32ac2..8ec015cbde9b 100644
--- a/drivers/video/tegra/dc/ext/dev.c
+++ b/drivers/video/tegra/dc/ext/dev.c
@@ -274,31 +274,40 @@ static int tegra_dc_ext_set_windowattr(struct tegra_dc_ext *ext,
 	return 0;
 }
 
-static struct srcu_notifier_head tegra_dc_flip_notifier_list;
-static bool init_tegra_dc_flip_notifier_list_called;
-static int __init init_tegra_dc_flip_notifier_list(void)
+static void (*flip_callback)(void);
+static spinlock_t flip_callback_lock;
+static bool init_tegra_dc_flip_callback_called;
+
+static int __init init_tegra_dc_flip_callback(void)
 {
-	srcu_init_notifier_head(&tegra_dc_flip_notifier_list);
-	init_tegra_dc_flip_notifier_list_called = true;
+	spin_lock_init(&flip_callback_lock);
+	init_tegra_dc_flip_callback_called = true;
 	return 0;
 }
 
-pure_initcall(init_tegra_dc_flip_notifier_list);
+pure_initcall(init_tegra_dc_flip_callback);
 
-int tegra_dc_register_flip_notifier(struct notifier_block *nb)
+int tegra_dc_set_flip_callback(void (*callback)(void))
 {
-	WARN_ON(!init_tegra_dc_flip_notifier_list_called);
+	WARN_ON(!init_tegra_dc_flip_callback_called);
+
+	spin_lock(&flip_callback_lock);
+	flip_callback = callback;
+	spin_unlock(&flip_callback_lock);
 
-	return srcu_notifier_chain_register(
-			&tegra_dc_flip_notifier_list, nb);
+	return 0;
 }
-EXPORT_SYMBOL(tegra_dc_register_flip_notifier);
+EXPORT_SYMBOL(tegra_dc_set_flip_callback);
 
-int tegra_dc_unregister_flip_notifier(struct notifier_block *nb)
+int tegra_dc_unset_flip_callback()
 {
-	return srcu_notifier_chain_unregister(&tegra_dc_flip_notifier_list, nb);
+	spin_lock(&flip_callback_lock);
+	flip_callback = NULL;
+	spin_unlock(&flip_callback_lock);
+
+	return 0;
 }
-EXPORT_SYMBOL(tegra_dc_unregister_flip_notifier);
+EXPORT_SYMBOL(tegra_dc_unset_flip_callback);
 
 static void tegra_dc_ext_flip_worker(struct work_struct *work)
 {
@@ -353,9 +362,12 @@ static void tegra_dc_ext_flip_worker(struct work_struct *work)
 		tegra_dc_update_windows(wins, nr_win);
 		/* TODO: implement swapinterval here */
 		tegra_dc_sync_windows(wins, nr_win);
-		if (!tegra_dc_has_multiple_dc())
-			srcu_notifier_call_chain(&tegra_dc_flip_notifier_list,
-						 1UL, NULL);
+		if (!tegra_dc_has_multiple_dc()) {
+			spin_lock(&flip_callback_lock);
+			if (flip_callback)
+				flip_callback();
+			spin_unlock(&flip_callback_lock);
+		}
 	}
 
 	for (i = 0; i < DC_N_WINDOWS; i++) {