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clk: Fixup errorhandling for clk_set_parent

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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: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
This commit is contained in:
Ulf Hansson 2013-04-02 23:09:38 +02:00 committed by Mike Turquette
parent b33d212f49
commit 031dcc9bd4
1 changed files with 36 additions and 20 deletions
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56
drivers/clk/clk.c
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@ -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);
@ -1360,11 +1355,14 @@ 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)
@ -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) {