linux-kernel - Re: [PATCH 4/7] clocksource: mips-gic: Update clockevent frequency on clock rate changes

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Date:	Thu, 21 May 2015 19:30:12 -0300
From:	Ezequiel Garcia <ezequiel.garcia@...tec.com>
To:	Andrew Bresticker <abrestic@...omium.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux-MIPS <linux-mips@...ux-mips.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	James Hartley <james.hartley@...tec.com>,
	James Hogan <james.hogan@...tec.com>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	Damien Horsley <Damien.Horsley@...tec.com>,
	Govindraj Raja <Govindraj.Raja@...tec.com>
Subject: Re: [PATCH 4/7] clocksource: mips-gic: Update clockevent frequency
 on clock rate changes



On 05/21/2015 07:32 PM, Andrew Bresticker wrote:
> On Thu, May 21, 2015 at 2:37 PM, Ezequiel Garcia
> <ezequiel.garcia@...tec.com> wrote:
>> This commit introduces the clockevent frequency update, using
>> a clock notifier. It will be used to support CPUFreq on platforms
>> using MIPS GIC based clockevents.
>>
>> Signed-off-by: Ezequiel Garcia <ezequiel.garcia@...tec.com>
>> ---
>>  drivers/clocksource/mips-gic-timer.c | 31 ++++++++++++++++++++++++++++++-
>>  1 file changed, 30 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/clocksource/mips-gic-timer.c b/drivers/clocksource/mips-gic-timer.c
>> index 22a4daf..71bbd42 100644
>> --- a/drivers/clocksource/mips-gic-timer.c
>> +++ b/drivers/clocksource/mips-gic-timer.c
>> @@ -79,6 +79,13 @@ static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
>>         disable_percpu_irq(gic_timer_irq);
>>  }
>>
>> +static void gic_update_frequency(void *data)
>> +{
>> +       unsigned long rate = (unsigned long)data;
>> +
>> +       clockevents_update_freq(this_cpu_ptr(&gic_clockevent_device), rate);
>> +}
>> +
>>  static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action,
>>                                 void *data)
>>  {
>> @@ -94,10 +101,26 @@ static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action,
>>         return NOTIFY_OK;
>>  }
>>
>> +static int gic_clk_notifier(struct notifier_block *nb, unsigned long action,
>> +                           void *data)
>> +{
>> +       struct clk_notifier_data *cnd = data;
>> +
>> +       if (action == POST_RATE_CHANGE)
>> +               on_each_cpu(gic_update_frequency, (void *)cnd->new_rate, 1);
>> +
>> +       return NOTIFY_OK;
>> +}
>> +
>> +
>>  static struct notifier_block gic_cpu_nb = {
>>         .notifier_call = gic_cpu_notifier,
>>  };
>>
>> +static struct notifier_block gic_clk_nb = {
>> +       .notifier_call = gic_clk_notifier,
>> +};
>> +
>>  static int gic_clockevent_init(void)
>>  {
>>         int ret;
>> @@ -160,6 +183,7 @@ void __init gic_clocksource_init(unsigned int frequency)
>>  static void __init gic_clocksource_of_init(struct device_node *node)
>>  {
>>         struct clk *clk;
>> +       int ret;
>>
>>         if (WARN_ON(!gic_present || !node->parent ||
>>                     !of_device_is_compatible(node->parent, "mti,gic")))
>> @@ -186,7 +210,12 @@ static void __init gic_clocksource_of_init(struct device_node *node)
>>         }
>>
>>         __gic_clocksource_init();
>> -       gic_clockevent_init();
>> +
>> +       ret = gic_clockevent_init();
>> +       if (ret < 0 && !IS_ERR(clk)) {
> 
> I think you mean ret == 0 here?
> 
>> +               if (clk_notifier_register(clk, &gic_clk_nb) < 0)
>> +                       pr_warn("GIC: Unable to register clock notifier\n");
>> +       }

Ouch, certainly.
-- 
Ezequiel
--
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