linux-kernel - Re: [RFC PATCH v2] clk: move check of CLK_SET_RATE_GATE flag to clk_propagate_rate

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Date:	Thu, 14 Jul 2016 14:15:31 +0900
From:	Jiada Wang <jiada_wang@...tor.com>
To:	Michael Turquette <mturquette@...libre.com>,
	<sboyd@...eaurora.org>, <linux-clk@...r.kernel.org>
CC:	<linux-kernel@...r.kernel.org>, <joshua_frkuska@...tor.com>,
	<vladimir_zapolskiy@...tor.com>
Subject: Re: [RFC PATCH v2] clk: move check of CLK_SET_RATE_GATE flag to clk_propagate_rate_change()

Hello Michael

On 07/13/2016 07:29 AM, Michael Turquette wrote:
> Quoting jiada_wang@...tor.com (2016-07-10 22:33:28)
>> From: Jiada Wang <jiada_wang@...tor.com>
>>
>> Previously CLK_SET_RATE_GATE flag is only checked in clk_set_rate()
>> which only ensures the clock being called by clk_set_rate() won't
>> change rate when it has been prepared if CLK_SET_RATE_GATE flag is set.
>> But a clk_set_rate() request may propagate rate change to these clocks
>> from the requested clock's topmost parent clock to all its offsprings,
>> when any one of these clocks has CLK_SET_RATE_GATE flag set
>> and it has been prepared, the clk_set_rate() request should fail.
>>
>> This patch moves check of CLK_SET_RATE_GATE flag to
>> clk_propagate_rate_change() to ensure all affected clocks will
>> be checked if their rate will be changed after clk_set_rate().
>>
>> Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
>> ---
>
> What's different in version 2? It's tradition to put a little version
> changelog here, below the "---" line and above the "diff --git a/..."
> line.
>
version 2 resolves the following kernel warning
"
    drivers/clk/clk.c: In function 'clk_propagate_rate_change':
 >> drivers/clk/clk.c:1441:3: warning: return makes pointer from integer 
without a cast
       return -EBUSY;
       ^
"
I forgot to add a changelog in v2 patch, sorry for the confusion caused.

Thanks,
Jiada
> Regards,
> Mike
>
>>   drivers/clk/clk.c |    6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>> index 820a939..2f930c8 100644
>> --- a/drivers/clk/clk.c
>> +++ b/drivers/clk/clk.c
>> @@ -1437,6 +1437,9 @@ static struct clk_core *clk_propagate_rate_change(struct clk_core *core,
>>          if (core->rate == core->new_rate)
>>                  return NULL;
>>
>> +       if ((core->flags & CLK_SET_RATE_GATE) && core->prepare_count)
>> +               return core;
>> +
>>          if (core->notifier_count) {
>>                  ret = __clk_notify(core, event, core->rate, core->new_rate);
>>                  if (ret & NOTIFY_STOP_MASK)
>> @@ -1571,9 +1574,6 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
>>          if (rate == clk_core_get_rate_nolock(core))
>>                  return 0;
>>
>> -       if ((core->flags & CLK_SET_RATE_GATE) && core->prepare_count)
>> -               return -EBUSY;
>> -
>>          /* calculate new rates and get the topmost changed clock */
>>          top = clk_calc_new_rates(core, rate);
>>          if (!top)
>> --
>> 1.7.9.5
>>
>>