;> really do the voltage scaling.
>>
>> Tegra devfreq driver will register clock notifiers on all its interested
>> clock and hence when any of those clock rate changes, disabled, enabled,
>> we'll specifically call updat
On 15 March 2013 20:38, Stephen Warren wrote:
> On 03/15/2013 06:33 AM, Ulf Hansson wrote:
>> On 15 March 2013 13:06, Bill Huang wrote:
>>> On Fri, 2013-03-15 at 18:08 +0800, Ulf Hansson wrote:
> ...
>>>> Some prerequisites; I think am in favor of using the clk
On 15 March 2013 13:06, Bill Huang wrote:
> On Fri, 2013-03-15 at 18:08 +0800, Ulf Hansson wrote:
>> On 15 March 2013 10:39, Peter De Schrijver wrote:
>> > On Fri, Mar 15, 2013 at 06:22:47AM +0100, Stephen Warren wrote:
>> >> On 03/14/2013 07:20 PM, Bill Huang wro
n this topic;
Some prerequisites; I think am in favor of using the clk API to
trigger DVFS changes and then I agree on that clk_prepare|unprepare
needs to be possible to track from a DVFS perspective. clk_set_rate is
not enough.
So if we decide to do the above (using the clk API to trigger DVFS
changes), I believe we should discuss two possible solutions;
- clk notifiers or..
- dvfs clock type.
I am trying to make up my mind of what I think is the best solution.
Have you considered "dvfs clock type"?
I put some comments about this for "[PATCH 2/5] clk: notifier handler
for dynamic voltage scaling" recently as well.
What could the advantages/disadvantages be between the two options?
Kind regards
Ulf Hansson
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first solution. Likely
less code in each driver but still "DVFS intelligence" need to exist
there.
>
> A hybrid solution might be to set a flag on a clock (e.g.
> CLK_SET_RATE_DVFS) which tells the clk framework that this clock is
> special and clk_set_rate should call d
_reentrant()) {
> + parent = __clk_get_parent(clk);
> + goto out;
> + }
> +
> + clk_fwk_lock();
> parent = __clk_get_parent(clk);
> - mutex_unlock(&prepare_lock);
> + clk_fwk_unlock();
>
> +out:
> return parent;
> }
> EXPORT_SYMBOL_GPL(clk_get_parent);
> @@ -1293,6 +1405,7 @@ out:
> int clk_set_parent(struct clk *clk, struct clk *parent)
> {
> int ret = 0;
> + bool reenter;
>
> if (!clk || !clk->ops)
> return -EINVAL;
> @@ -1300,8 +1413,10 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
> if (!clk->ops->set_parent)
> return -ENOSYS;
>
> - /* prevent racing with updates to the clock topology */
> - mutex_lock(&prepare_lock);
> + reenter = clk_is_reentrant();
> +
> + if (!reenter)
> + clk_fwk_lock();
>
> if (clk->parent == parent)
> goto out;
> @@ -1330,7 +1445,8 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
> __clk_reparent(clk, parent);
>
> out:
> - mutex_unlock(&prepare_lock);
> + if (!reenter)
> + clk_fwk_unlock();
>
> return ret;
> }
> --
> 1.7.10.4
>
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Kind regards
Ulf Hansson
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