linux-kernel - Re: [PATCH v12 04/10] clk: use struct clk only for external API

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Date:	Tue, 23 Sep 2014 11:09:05 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	Mike Turquette <mturquette@...aro.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Peter De Schrijver <pdeschrijver@...dia.com>,
	linux-kernel@...r.kernel.org, tomasz.figa@...il.com, rabin@....in,
	Thierry Reding <thierry.reding@...il.com>,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v12 04/10] clk: use struct clk only for external API

On 09/22/2014 08:08 PM, Russell King - ARM Linux wrote:
> On Mon, Sep 22, 2014 at 04:15:47PM +0200, Tomeu Vizoso wrote:
>> diff --git a/drivers/clk/clk.h b/drivers/clk/clk.h
>> index d278572..3b3068b 100644
>> --- a/drivers/clk/clk.h
>> +++ b/drivers/clk/clk.h
>> @@ -9,9 +9,15 @@
>>   * published by the Free Software Foundation.
>>   */
>>  
>> +#include <linux/clk-private.h>
>> +
>>  #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
>>  struct clk_core *of_clk_get_by_clkspec(struct of_phandle_args *clkspec);
>>  struct clk_core *__of_clk_get_from_provider(struct of_phandle_args *clkspec);
>>  void of_clk_lock(void);
>>  void of_clk_unlock(void);
>>  #endif
>> +
>> +#if defined(CONFIG_COMMON_CLK)
>> +struct clk *__clk_create_clk(struct clk_core *clk_core);
>> +#endif
> 
> Why does any of the above need ifdefs?

Because struct clk_core is only defined if CONFIG_COMMON_CLK, so clock
implementations that don't use the CCF don't have to be converted to
clk_core.

>> diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
>> index c751d0c..060041b 100644
>> --- a/drivers/clk/clkdev.c
>> +++ b/drivers/clk/clkdev.c
>> @@ -18,6 +18,7 @@
>>  #include <linux/string.h>
>>  #include <linux/mutex.h>
>>  #include <linux/clk.h>
>> +#include <linux/clk-private.h>
>>  #include <linux/clk-provider.h>
>>  #include <linux/clkdev.h>
>>  #include <linux/of.h>
>> @@ -33,13 +34,13 @@ static DEFINE_MUTEX(clocks_mutex);
> 
> I'm not happy with any of these changes, because it introduces a huge
> number of ifdefs.
> 
> Instead of doing this, please introduce a local typedef in this .c file
> which is conditional on whether we're using your new struct clk_core
> or not, eg, clkdev_ret_t.
> 
> Then, rename all the functions here to be _provider based, and arrange
> for these to return clkdev_ret_t.
> 
> Then provide the original functions, with your __clk_create_clk() call
> to allocate your struct clk.  A dummy version which merely returns its
> argument can be provided when we're not using clk_core.
> 
> This should result in substantially fewer ifdefs - probably just one
> ifdef.

Sounds like a neat improvement, will send soon v13 with this.

> Another concern here is what happens when __clk_create_clk() fails.
> Your __clk_create_clk() function does nothing in that regard, so any
> references which the parent function took are never released.

Yeah, will address this in v13 as well.

Thanks a lot for the feedback,

Tomeu

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