Commit 63f5c3b2 authored May 02, 2012 by Mike Turquette

clk: prevent spurious parent rate propagation



Patch 'clk: always pass parent_rate into .round_rate' made a subtle
change to the semantics of .round_rate.  It is now expected for the
parent's rate to always be passed in, simplifying the implemenation of
various .round_rate callback definitions.

However the patch also introduced a bug in clk_calc_new_rates whereby a
clock without the CLK_SET_RATE_PARENT flag set could still propagate a
rate change up to a parent clock if the the .round_rate callback
modified the &best_parent_rate value in any way.

This patch fixes the issue at the framework level (in
clk_calc_new_rates) by specifically handling the case where the
CLK_SET_RATE_PARENT flag is not set.

Signed-off-by: Mike Turquette <mturquette@linaro.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>

parent 7704addb

drivers/clk/clk.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -774,12 +774,18 @@ static struct clk clk_calc_new_rates(struct clk clk, unsigned long rate)
		if (IS_ERR_OR_NULL(clk))
		return NULL;

		/* save parent rate, if it exists */
		if (clk->parent)
		best_parent_rate = clk->parent->rate;

		/* never propagate up to the parent */
		if (!(clk->flags & CLK_SET_RATE_PARENT)) {
		if (!clk->ops->round_rate) {
		clk->new_rate = clk->rate;
		return NULL;
		}
		new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
		goto out;
		}

		/* need clk->parent from here on out */
		@@ -795,7 +801,6 @@ static struct clk clk_calc_new_rates(struct clk clk, unsigned long rate)
		goto out;
		}

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

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