linux-kernel - Re: [PATCH] clk: Fix notifier documentation

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Message-ID: <CAPtuhTj7QmB-xFU40x_MCvbvo07M2_2sDfiOQNkf4oEGFPKiOg@mail.gmail.com>
Date:	Fri, 31 Jan 2014 22:01:27 -0800
From:	Mike Turquette <mturquette@...aro.org>
To:	Sören Brinkmann <soren.brinkmann@...inx.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] clk: Fix notifier documentation

On Fri, Jan 31, 2014 at 5:49 PM, Sören Brinkmann
<soren.brinkmann@...inx.com> wrote:
> ping?

Hi Soren,

I'm a bit slow to review patches during the merge window. Thanks for
the doc update. I'll take it in after -rc1 drops.

Regards,
Mik

>
> On Wed, Jan 22, 2014 at 11:48:37AM -0800, Soren Brinkmann wrote:
>> Contradicting to documenation, the notifier callbacks do receive
>> the original clock rate in struct clk_notifier_data.old_rate and the new
>> frequency struct clk_notifier_data.new_rate, independent of the
>> notification reason.
>>
>> This behavior also seems to make more sense, since callbacks can use the
>> same code to deterimine whether clocks are scaled up or down. Something
>> which would not even possible in the post-rate-change case if the
>> behavior was as documented.
>>
>> Signed-off-by: Soren Brinkmann <soren.brinkmann@...inx.com>
>> ---
>> Hi Mike,
>>
>> I am working with some clock notifiers and if my results are correct the
>> notifiers behave differently from how they are documented.
>> I think the actual behavior makes more sense than the documented and my original
>> plan was to change the behavior, but it seems I might get away with a
>> doc-update.
>>
>>       Thanks,
>>       Sören
>>
>>  drivers/clk/clk.c | 15 +++------------
>>  1 file changed, 3 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>> index 2cf2ea6b77a1..26825db03e64 100644
>> --- a/drivers/clk/clk.c
>> +++ b/drivers/clk/clk.c
>> @@ -1983,20 +1983,11 @@ EXPORT_SYMBOL_GPL(devm_clk_unregister);
>>   * re-enter into the clk framework by calling any top-level clk APIs;
>>   * this will cause a nested prepare_lock mutex.
>>   *
>> - * Pre-change notifier callbacks will be passed the current, pre-change
>> - * rate of the clk via struct clk_notifier_data.old_rate.  The new,
>> - * post-change rate of the clk is passed via struct
>> + * In all notification cases cases (pre, post and abort rate change) the
>> + * original clock rate is passed to the callback via struct
>> + * clk_notifier_data.old_rate and the new frequency is passed via struct
>>   * clk_notifier_data.new_rate.
>>   *
>> - * Post-change notifiers will pass the now-current, post-change rate of
>> - * the clk in both struct clk_notifier_data.old_rate and struct
>> - * clk_notifier_data.new_rate.
>> - *
>> - * Abort-change notifiers are effectively the opposite of pre-change
>> - * notifiers: the original pre-change clk rate is passed in via struct
>> - * clk_notifier_data.new_rate and the failed post-change rate is passed
>> - * in via struct clk_notifier_data.old_rate.
>> - *
>>   * clk_notifier_register() must be called from non-atomic context.
>>   * Returns -EINVAL if called with null arguments, -ENOMEM upon
>>   * allocation failure; otherwise, passes along the return value of
>> --
>> 1.8.5.3
>>
>>
>
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