Commit 031dcc9b authored by Ulf Hansson's avatar Ulf Hansson Committed by Mike Turquette
Browse files

clk: Fixup errorhandling for clk_set_parent 



Fixup the broken feature of allowing reparent of a clk to the
orhpan list and vice verse. When operating on a single-parent
clk, the .set_parent callback for the clk hw is optional to
implement, but for a multi-parent clk it is mandatory.

Moreover improve the errorhandling by verifying the prerequisites
before triggering clk notifiers. This will prevent unnecessary
rollback with ABORT_RATE_CHANGE.

Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
parent b33d212f

drivers/clk/clk.c

+36 −20
Original line number Diff line number Diff line
@@ -1332,15 +1332,10 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent) 
	__clk_recalc_rates(clk, POST_RATE_CHANGE);

}



static int __clk_set_parent(struct clk *clk, struct clk *parent)

static u8 clk_fetch_parent_index(struct clk *clk, struct clk *parent)

{

	struct clk *old_parent;

	unsigned long flags;

	int ret = -EINVAL;

	u8 i;



	old_parent = clk->parent;



	if (!clk->parents)

		clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),

								GFP_KERNEL);
@@ -1360,12 +1355,15 @@ static int __clk_set_parent(struct clk *clk, struct clk *parent) 
		}

	}



	if (i == clk->num_parents) {

		pr_debug("%s: clock %s is not a possible parent of clock %s\n",

				__func__, parent->name, clk->name);

		goto out;

	return i;

}



static int __clk_set_parent(struct clk *clk, struct clk *parent, u8 p_index)

{

	unsigned long flags;

	int ret = 0;

	struct clk *old_parent = clk->parent;



	/* migrate prepare and enable */

	if (clk->prepare_count)

		__clk_prepare(parent);
@@ -1377,7 +1375,8 @@ static int __clk_set_parent(struct clk *clk, struct clk *parent) 
	clk_enable_unlock(flags);



	/* change clock input source */

	ret = clk->ops->set_parent(clk->hw, i);

	if (parent && clk->ops->set_parent)

		ret = clk->ops->set_parent(clk->hw, p_index);



	/* clean up old prepare and enable */

	flags = clk_enable_lock();
@@ -1388,7 +1387,6 @@ static int __clk_set_parent(struct clk *clk, struct clk *parent) 
	if (clk->prepare_count)

		__clk_unprepare(old_parent);



out:

	return ret;

}
@@ -1407,11 +1405,14 @@ out: 
int clk_set_parent(struct clk *clk, struct clk *parent)

{

	int ret = 0;

	u8 p_index = 0;

	unsigned long p_rate = 0;



	if (!clk || !clk->ops)

		return -EINVAL;



	if (!clk->ops->set_parent)

	/* verify ops for for multi-parent clks */

	if ((clk->num_parents > 1) && (!clk->ops->set_parent))

		return -ENOSYS;



	/* prevent racing with updates to the clock topology */
@@ -1420,19 +1421,34 @@ int clk_set_parent(struct clk *clk, struct clk *parent) 
	if (clk->parent == parent)

		goto out;



	/* check that we are allowed to re-parent if the clock is in use */

	if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) {

		ret = -EBUSY;

		goto out;

	}



	/* try finding the new parent index */

	if (parent) {

		p_index = clk_fetch_parent_index(clk, parent);

		p_rate = parent->rate;

		if (p_index == clk->num_parents) {

			pr_debug("%s: clk %s can not be parent of clk %s\n",

					__func__, parent->name, clk->name);

			ret = -EINVAL;

			goto out;

		}

	}



	/* propagate PRE_RATE_CHANGE notifications */

	if (clk->notifier_count)

		ret = __clk_speculate_rates(clk, parent->rate);

		ret = __clk_speculate_rates(clk, p_rate);



	/* abort if a driver objects */

	if (ret == NOTIFY_STOP)

		goto out;



	/* only re-parent if the clock is not in use */

	if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count)

		ret = -EBUSY;

	else

		ret = __clk_set_parent(clk, parent);

	/* do the re-parent */

	ret = __clk_set_parent(clk, parent, p_index);



	/* propagate ABORT_RATE_CHANGE if .set_parent failed */

	if (ret) {

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