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List:       linux-omap
Subject:    Re: [PATCH v13 4/6] clk: Add rate constraints to clocks
From:       Tomeu Vizoso <tomeu.vizoso () collabora ! com>
Date:       2015-01-31 18:36:22
Message-ID: CAAObsKDxhV7Vveq5FizTUp9ur2Rsq1bM+YQa4uPksh5ntMQV3Q () mail ! gmail ! com
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On 31 January 2015 at 02:31, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 01/29, Stephen Boyd wrote:
>> On 01/29/15 05:31, Geert Uytterhoeven wrote:
>> > Hi Tomeu, Mike,
>> >
>> > On Fri, Jan 23, 2015 at 12:03 PM, Tomeu Vizoso
>> > <tomeu.vizoso@collabora.com> wrote:
>> >> --- a/drivers/clk/clk.c
>> >> +++ b/drivers/clk/clk.c
>> >> @@ -2391,25 +2543,24 @@ int __clk_get(struct clk *clk)
>> >>         return 1;
>> >>  }
>> >>
>> >> -static void clk_core_put(struct clk_core *core)
>> >> +void __clk_put(struct clk *clk)
>> >>  {
>> >>         struct module *owner;
>> >>
>> >> -       owner = core->owner;
>> >> +       if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
>> >> +               return;
>> >>
>> >>         clk_prepare_lock();
>> >> -       kref_put(&core->ref, __clk_release);
>> >> +
>> >> +       hlist_del(&clk->child_node);
>> >> +       clk_core_set_rate_nolock(clk->core, clk->core->req_rate);
>> > At this point, clk->core->req_rate is still zero, causing
>> > cpg_div6_clock_round_rate() to be called with a zero "rate" parameter,
>> > e.g. on r8a7791:
>>
>> Hmm.. I wonder if we should assign core->req_rate to be the same as
>> core->rate during __clk_init()? That would make this call to
>> clk_core_set_rate_nolock() a nop in this case.
>>
>
> Here's a patch to do this
>
> ---8<----
> From: Stephen Boyd <sboyd@codeaurora.org>
> Subject: [PATCH] clk: Assign a requested rate by default
>
> We need to assign a requested rate here so that we avoid
> requesting a rate of 0 on clocks when we remove clock consumers.

Hi, this looks good to me.

Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>

Thanks,

Tomeu

> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> ---
>  drivers/clk/clk.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index a29daf9edea4..8416ed1c40be 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -2142,6 +2142,7 @@ int __clk_init(struct device *dev, struct clk *clk_user)
>         struct clk_core *orphan;
>         struct hlist_node *tmp2;
>         struct clk_core *clk;
> +       unsigned long rate;
>
>         if (!clk_user)
>                 return -EINVAL;
> @@ -2266,12 +2267,13 @@ int __clk_init(struct device *dev, struct clk *clk_user)
>          * then rate is set to zero.
>          */
>         if (clk->ops->recalc_rate)
> -               clk->rate = clk->ops->recalc_rate(clk->hw,
> +               rate = clk->ops->recalc_rate(clk->hw,
>                                 clk_core_get_rate_nolock(clk->parent));
>         else if (clk->parent)
> -               clk->rate = clk->parent->rate;
> +               rate = clk->parent->rate;
>         else
> -               clk->rate = 0;
> +               rate = 0;
> +       clk->rate = clk->req_rate = rate;
>
>         /*
>          * walk the list of orphan clocks and reparent any that are children of
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
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