2015-02-02 22:11:30

by Stephen Boyd

Subject: [PATCH] clk: clk_set_parent() with current parent shouldn't fail

If a driver calls clk_set_parent(clk, parent) and parent is the
current parent of clk we shouldn't fail in any case.
Unfortunately if clk is a read-only mux we return -ENOSYS
because we think we can't change the parent, except for in this
special case where we don't actually need to change the parent at
all. Return 0 in such a situation.

Cc: Philipp Zabel <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>
---

Based on clk-next

drivers/clk/clk.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index b82714a84f5e..670c8c86ce9f 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1969,16 +1969,18 @@ static int clk_core_set_parent(struct clk_core *clk, struct clk_core *parent)
if (!clk)
return 0;

- /* 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 */
clk_prepare_lock();

if (clk->parent == parent)
goto out;

+ /* verify ops for for multi-parent clks */
+ if ((clk->num_parents > 1) && (!clk->ops->set_parent)) {
+ ret = -ENOSYS;
+ 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;
--
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2015-02-03 09:42:41

by Philipp Zabel

Subject: Re: [PATCH] clk: clk_set_parent() with current parent shouldn't fail

Am Montag, den 02.02.2015, 14:11 -0800 schrieb Stephen Boyd:
> If a driver calls clk_set_parent(clk, parent) and parent is the
> current parent of clk we shouldn't fail in any case.
> Unfortunately if clk is a read-only mux we return -ENOSYS
> because we think we can't change the parent, except for in this
> special case where we don't actually need to change the parent at
> all. Return 0 in such a situation.
>
> Cc: Philipp Zabel <[email protected]>
> Signed-off-by: Stephen Boyd <[email protected]>

Acked-by: Philipp Zabel <[email protected]>

regards
Philipp

2015-02-25 20:46:43

by Mike Turquette

Subject: Re: [PATCH] clk: clk_set_parent() with current parent shouldn't fail

Quoting Philipp Zabel (2015-02-03 01:42:34)
> Am Montag, den 02.02.2015, 14:11 -0800 schrieb Stephen Boyd:
> > If a driver calls clk_set_parent(clk, parent) and parent is the
> > current parent of clk we shouldn't fail in any case.
> > Unfortunately if clk is a read-only mux we return -ENOSYS
> > because we think we can't change the parent, except for in this
> > special case where we don't actually need to change the parent at
> > all. Return 0 in such a situation.
> >
> > Cc: Philipp Zabel <[email protected]>
> > Signed-off-by: Stephen Boyd <[email protected]>
>
> Acked-by: Philipp Zabel <[email protected]>

Applied to clk-next.

Regards,
Mike

>
> regards
> Philipp
>