From 44aa223a3e4ab5c3ea59e916899a3695b0dac06d Mon Sep 17 00:00:00 2001
From: Taniya Das <tdas@codeaurora.org>
Date: Sat, 3 Dec 2016 20:35:23 +0530
Subject: [PATCH] clk: move check for CLK_ENABLE_HAND_OFF at unused tree

The commit 04a0136aeea5 ("clk: introduce CLK_ENABLE_HAND_OFF flag")
assumes that the first time clock client calls a clk_prepare &
clk_enable, the clocks from that point of time could be on their own.
But there could be use cases which could have impacts due to this
handling. Moving the handoff counts for prepare and enable at unused
tree level.

Change-Id: I7d527571c2eb4d53d58d82126989bd673de12e2d
Signed-off-by: Taniya Das <tdas@codeaurora.org>
---
 drivers/clk/clk.c | 78 +++++++++++++++++++++++++----------------------
 1 file changed, 42 insertions(+), 36 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 55b44559bae4..ac815c6dbac0 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -197,6 +197,19 @@ static void clk_unprepare_unused_subtree(struct clk_core *core)
 	hlist_for_each_entry(child, &core->children, child_node)
 		clk_unprepare_unused_subtree(child);
 
+	/*
+	 * setting CLK_ENABLE_HAND_OFF flag triggers this conditional
+	 *
+	 * need_handoff_prepare implies this clk was already prepared by
+	 * __clk_init. now we have a proper user, so unset the flag in our
+	 * internal bookkeeping. See CLK_ENABLE_HAND_OFF flag in clk-provider.h
+	 * for details.
+	 */
+	if (core->need_handoff_prepare) {
+		core->need_handoff_prepare = false;
+		core->prepare_count--;
+	}
+
 	if (core->prepare_count)
 		return;
 
@@ -223,6 +236,19 @@ static void clk_disable_unused_subtree(struct clk_core *core)
 	hlist_for_each_entry(child, &core->children, child_node)
 		clk_disable_unused_subtree(child);
 
+	/*
+	 * setting CLK_ENABLE_HAND_OFF flag triggers this conditional
+	 *
+	 * need_handoff_enable implies this clk was already enabled by
+	 * __clk_init. now we have a proper user, so unset the flag in our
+	 * internal bookkeeping. See CLK_ENABLE_HAND_OFF flag in clk-provider.h
+	 * for details.
+	 */
+	if (core->need_handoff_enable) {
+		core->need_handoff_enable = false;
+		core->enable_count--;
+	}
+
 	flags = clk_enable_lock();
 
 	if (core->enable_count)
@@ -932,24 +958,10 @@ int clk_prepare(struct clk *clk)
 	if (!clk)
 		return 0;
 
-	/*
-	 * setting CLK_ENABLE_HAND_OFF flag triggers this conditional
-	 *
-	 * need_handoff_prepare implies this clk was already prepared by
-	 * __clk_init. now we have a proper user, so unset the flag in our
-	 * internal bookkeeping. See CLK_ENABLE_HAND_OFF flag in clk-provider.h
-	 * for details.
-	 */
-	if (clk->core->need_handoff_prepare) {
-		clk->core->need_handoff_prepare = false;
-		goto out;
-	}
-
 	clk_prepare_lock();
 	ret = clk_core_prepare(clk->core);
 	clk_prepare_unlock();
 
-out:
 	return ret;
 }
 EXPORT_SYMBOL_GPL(clk_prepare);
@@ -1061,24 +1073,10 @@ int clk_enable(struct clk *clk)
 	if (!clk)
 		return 0;
 
-	/*
-	 * setting CLK_ENABLE_HAND_OFF flag triggers this conditional
-	 *
-	 * need_handoff_enable implies this clk was already enabled by
-	 * __clk_init. now we have a proper user, so unset the flag in our
-	 * internal bookkeeping. See CLK_ENABLE_HAND_OFF flag in clk-provider.h
-	 * for details.
-	 */
-	if (clk->core->need_handoff_enable) {
-		clk->core->need_handoff_enable = false;
-		goto out;
-	}
-
 	flags = clk_enable_lock();
 	ret = clk_core_enable(clk->core);
 	clk_enable_unlock(flags);
 
-out:
 	return ret;
 }
 EXPORT_SYMBOL_GPL(clk_enable);
@@ -3189,14 +3187,22 @@ static int __clk_init(struct device *dev, struct clk *clk_user)
 	if (core->flags & CLK_ENABLE_HAND_OFF) {
 		unsigned long flags;
 
-		core->need_handoff_prepare = true;
-		core->need_handoff_enable = true;
-		ret = clk_core_prepare(core);
-		if (ret)
-			goto out;
-		flags = clk_enable_lock();
-		clk_core_enable(core);
-		clk_enable_unlock(flags);
+		/*
+		 * Few clocks might have hardware gating which would be required
+		 * to be ON before prepare/enabling the clocks. So check if the
+		 * clock has been turned ON earlier and we should
+		 * prepare/enable those clocks.
+		 */
+		if (clk_core_is_enabled(core)) {
+			core->need_handoff_prepare = true;
+			core->need_handoff_enable = true;
+			ret = clk_core_prepare(core);
+			if (ret)
+				goto out;
+			flags = clk_enable_lock();
+			clk_core_enable(core);
+			clk_enable_unlock(flags);
+		}
 	}
 
 	kref_init(&core->ref);