Re: [Patch 3/3] clk: Avoid re-parenting orphan clk's having invalidparent index.

From: Ambresh K
Date: Tue Jun 04 2013 - 03:17:30 EST




On Wednesday 29 May 2013 12:48 PM, Mike Turquette wrote:
> Quoting Ambresh K (2013-05-01 23:25:29)
>> From: Ambresh K <ambresh@xxxxxx>
>>
>> Add orhan clk nodes having invalid parent index to list and use
>> the list to skip re-parenting orphan clk having invalid parents.
>>
>> Signed-off-by: Ambresh K <ambresh@xxxxxx>
>> ---
>> drivers/clk/clk.c | 21 +++++++++++++++++++--
>> 1 files changed, 19 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>> index f4d2c73..54d2aa3 100644
>> --- a/drivers/clk/clk.c
>> +++ b/drivers/clk/clk.c
>> @@ -32,6 +32,7 @@ static int enable_refcnt;
>>
>> static HLIST_HEAD(clk_root_list);
>> static HLIST_HEAD(clk_orphan_list);
>> +static HLIST_HEAD(clk_orphan_invalid_parent);
>
> Why not re-use the clk_orphan_list? Having an invalid value programmed
> into the hardware for selecting a parent essetially orphans a clock
> from a software point of view. Is there a specific need for the new
> list?

Sorry for not being descriptive in commit message.

a) Avoids unnecessary re-parenting cycle for orphan clock's with invalid parent for every clock

b) With patch [1/3], after a clk with invalid parent was encountered, for every clk registered thereafter seeing following logs.
<Snippet>
[ 0.000000] __clk_init: orphan clk(gpu_core_gclk_mux) invalid parent
[ 0.000000] __clk_init: orphan clk(gpu_core_gclk_mux) invalid parent
[ 0.000000] __clk_init: orphan clk(gpu_core_gclk_mux) invalid parent
[ 0.000000] __clk_init: orphan clk(gpu_core_gclk_mux) invalid parent
[ 0.000000] __clk_init: orphan clk(gpu_core_gclk_mux) invalid parent
[ 0.000000] __clk_init: orphan clk(gpu_core_gclk_mux) invalid parent
[ 0.000000] __clk_init: orphan clk(gpu_core_gclk_mux) invalid parent
[ 0.000000] __clk_init: orphan clk(gpu_core_gclk_mux) invalid parent

Please advice, if can be handled better.

Thanks,
Ambresh


>
> Regards,
> Mike
>
>> static LIST_HEAD(clk_notifier_list);
>>
>> /*** locking ***/
>> @@ -1532,8 +1533,8 @@ EXPORT_SYMBOL_GPL(clk_set_parent);
>> */
>> int __clk_init(struct device *dev, struct clk *clk)
>> {
>> - int i, ret = 0;
>> - struct clk *orphan;
>> + int i, ret = 0, skip = 0;
>> + struct clk *orphan, *has_invalid_parent;
>> struct hlist_node *tmp2;
>>
>> if (!clk)
>> @@ -1639,11 +1640,27 @@ int __clk_init(struct device *dev, struct clk *clk)
>> if (!strcmp(clk->name, orphan->name))
>> continue;
>>
>> + /* Skip iteration if orphan has invalid parent */
>> + hlist_for_each_entry(has_invalid_parent,
>> + &clk_orphan_invalid_parent, child_node) {
>> + if (!strcmp(orphan->name, has_invalid_parent->name)) {
>> + skip = 1;
>> + break;
>> + }
>> + }
>> +
>> + if (skip) {
>> + skip = 0;
>> + continue;
>> + }
>> +
>> if (orphan->ops->get_parent) {
>> i = orphan->ops->get_parent(orphan->hw);
>> if (i < 0) {
>> pr_err("%s: orphan clk(%s) invalid parent\n",
>> __func__, orphan->name);
>> + hlist_add_head(&orphan->child_node,
>> + &clk_orphan_invalid_parent);
>> continue;
>> }
>> if (!strcmp(clk->name, orphan->parent_names[i]))
>> --
>> 1.7.4.1
>
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