linux-kernel - Re: [PATCH] clk: add api to get clk consummer from clk

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Date:   Thu, 28 May 2020 20:50:25 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Stephen Boyd <sboyd@...nel.org>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: add api to get clk consummer from clk_hw


On Wed 27 May 2020 at 11:17, Stephen Boyd <sboyd@...nel.org> wrote:

> Quoting Jerome Brunet (2020-05-19 10:04:40)
>> clk_register() is deprecated. Using 'clk' member of struct clk_hw is
>> discouraged. With this constrainst, it is difficult for driver to
>
> s/constrainst/constraint/
>
>> register clocks using the clk_hw API and then use the clock with
>> the consummer API
>
> s/consummer/consumer/
>
>> 
>> This add a simple helper, clk_hw_get_clk(), to get a struct clk from
>> a struct clk_hw. Like other clk_get() variant, each call to this helper
>> must be balanced with a call to clk_put().
>> 
>> Cc: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
>> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
>
> I like it!
>
>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>> index 6fd23ce3cb03..d9946e192cbc 100644
>> --- a/drivers/clk/clk.c
>> +++ b/drivers/clk/clk.c
>> @@ -3625,6 +3625,23 @@ struct clk *clk_hw_create_clk(struct device *dev, struct clk_hw *hw,
>>         return clk;
>>  }
>>  
>> +/**
>> + * clk_hw_get_clk: get clk consummer given an clk_hw
>
> s/consummer/consumer/
>
>> + * @hw: clk_hw associated with the clk being consumed
>> + *
>> + * Returns: new clk consummer
>> + * This is the function to be used by providers which need
>> + * to get a consummer clk and act on the clock element
>
> s/consummer/consumer/
>
>> + * Calls to this function must be balanced with calls clk_put()
>
> calls to clk_put()
>
>> + */
>> +struct clk *clk_hw_get_clk(struct clk_hw *hw)

Sorry about all the typos ...

>
> Can it also take a const char *id argument? That will let us "name" the
> clk structure for situations where we want to keep track of who is using
> the clk pointer for things. If that doesn't seem useful then I suppose
> we can pass a string like "clk_hw_get_clk" for con_id below and hope it
> doesn't become useful later.

Sure I can add the argument. no worries

>
>> +{
>> +       struct device *dev = hw->core->dev;
>> +
>> +       return clk_hw_create_clk(dev, hw, dev_name(dev), NULL);
>> +}
>> +EXPORT_SYMBOL(clk_hw_get_clk);
>> +
>>  static int clk_cpy_name(const char **dst_p, const char *src, bool must_exist)
>>  {
>>         const char *dst;