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>

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 8149764..7ceca0e 100644 (file)
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -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) {