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Commit 7452b219 authored by Mike Turquette's avatar Mike Turquette
Browse files

clk: core: clk_calc_new_rates handles NULL parents 



It is possible to call clk_set_rate on a clock with a NULL parent.  One
such example is an adjustable-rate root clock.  Ensure that
clk_calc_new_rates does not dereference parent without checking first
and also handle the corner cases gracefully.

Reported-by: default avatarRajendra Nayak <rnayak@ti.com>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
parent 70d347e6

drivers/clk/clk.c

+21 −8
Original line number Original line Diff line number Diff line
@@ -763,25 +763,38 @@ static void clk_calc_subtree(struct clk *clk, unsigned long new_rate) 
static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)

static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)

{

{

	struct clk *top = clk;

	struct clk *top = clk;

	unsigned long best_parent_rate = clk->parent->rate;

	unsigned long best_parent_rate;

	unsigned long new_rate;

	unsigned long new_rate;





	if (!clk->ops->round_rate && !(clk->flags & CLK_SET_RATE_PARENT)) {

	/* sanity */

	if (IS_ERR_OR_NULL(clk))

		return NULL;



	/* never propagate up to the parent */

	if (!(clk->flags & CLK_SET_RATE_PARENT)) {

		if (!clk->ops->round_rate) {

			clk->new_rate = clk->rate;

			clk->new_rate = clk->rate;

			return NULL;

			return NULL;

		} else {

			new_rate = clk->ops->round_rate(clk->hw, rate, NULL);

			goto out;

		}

	}



	/* need clk->parent from here on out */

	if (!clk->parent) {

		pr_debug("%s: %s has NULL parent\n", __func__, clk->name);

		return NULL;

	}

	}





	if (!clk->ops->round_rate && (clk->flags & CLK_SET_RATE_PARENT)) {

	if (!clk->ops->round_rate) {

		top = clk_calc_new_rates(clk->parent, rate);

		top = clk_calc_new_rates(clk->parent, rate);

		new_rate = clk->new_rate = clk->parent->new_rate;

		new_rate = clk->new_rate = clk->parent->new_rate;





		goto out;

		goto out;

	}

	}





	if (clk->flags & CLK_SET_RATE_PARENT)

	new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);

	new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);

	else

		new_rate = clk->ops->round_rate(clk->hw, rate, NULL);





	if (best_parent_rate != clk->parent->rate) {

	if (best_parent_rate != clk->parent->rate) {

		top = clk_calc_new_rates(clk->parent, best_parent_rate);

		top = clk_calc_new_rates(clk->parent, best_parent_rate);