Re: [PATCH] clk: add strict of_clk_init dependency check

Date: Wed Feb 05 2014 - 10:14:16 EST

On 05/02/2014 16:05, Gregory CLEMENT wrote:
On 05/02/2014 15:48, Gregory CLEMENT wrote:
Hi Boris,

On 05/02/2014 10:48, Boris BREZILLON wrote:
The parent dependency check is only available on the first parent of a given

Add support for strict dependency check: all parents of a given clk must be

Signed-off-by: Boris BREZILLON <b.brezillon@xxxxxxxxxxx>

Hello Gregory,

This patch adds support for strict check on clk dependencies (check if all
parents specified by an DT clk node are initialized).

I'm not sure this is what you were expecting (maybe testing the first parent
is what you really want), so please feel free to tell me if I'm wrong.

Best Regards,


drivers/clk/clk.c | 27 +++++++++++++++++++++------
1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index beb0f8b..6849769 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2543,22 +2543,37 @@ static int parent_ready(struct device_node *np)
struct of_phandle_args clkspec;
struct of_clk_provider *provider;
+ int num_parents;
+ bool found;
+ int i;
* If there is no clock parent, no need to wait for them, then
* we can consider their absence as being ready
- if (of_parse_phandle_with_args(np, "clocks", "#clock-cells", 0,
- &clkspec))
+ num_parents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
+ if (num_parents <= 0)
return 1;
- /* Check if we have such a provider in our array */
- list_for_each_entry(provider, &of_clk_providers, link) {
- if (provider->node ==
+ for (i = 0; i < num_parents; i++) {
+ if (of_parse_phandle_with_args(np, "clocks", "#clock-cells", i,
+ &clkspec))
return 1;
+ /* Check if we have such a provider in our array */
+ found = false;
+ list_for_each_entry(provider, &of_clk_providers, link) {
+ if (provider->node == {
+ found = true;
+ break;
Hum this means that as soon as you have one parent then you consider it
as ready. It is better of what I have done because I only test the 1st
parent. However I wondered if we should go further by ensuring all the
parents are ready.
My bad, I read the code too fast. Your code already checks that all the
parents are ready.

So if you agree I will merge your code with mine and send a new patch.

That's fine by me.

If I am right, there is more than one parent only for the muxer. In this
case is it really expected that all the parent are ready?



+ }
+ }
+ if (!found)
+ return 0;
- return 0;
+ return 1;

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