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authorUlf Hansson <ulf.hansson@linaro.org>2013-04-02 23:09:38 +0200
committerMike Turquette <mturquette@linaro.org>2013-04-08 18:19:32 -0700
commit031dcc9bd4164a7482b89987d5b9ecb3af5e9033 (patch)
treeacab66af5c502cd7ad651de07356e33d3ad36b3b
parentb33d212f4910ca44bd37d5e08422230687bd1378 (diff)
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: Ulf Hansson <ulf.hansson@linaro.org> Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org> Signed-off-by: Mike Turquette <mturquette@linaro.org>
-rw-r--r--drivers/clk/clk.c56
1 files changed, 36 insertions, 20 deletions
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 013a3c7fea5b..c83e8e543bab 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -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) {