Message-ID: <51C8B551.9080203@st.com>
Date: Mon, 24 Jun 2013 22:08:33 +0100
From: Srinivas KANDAGATLA <srinivas.kandagatla@st.com>
Reply-To: srinivas.kandagatla@st.com
Organization: STMicroelectronics
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To: Stephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>, Thomas Gleixner <tglx@linutronix.de>,
        Grant Likely <grant.likely@linaro.org>,
        Rob Herring <rob.herring@calxeda.com>, Rob Landley <rob@landley.net>,
        devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Linus Walleij <linus.walleij@linaro.org>,
        Stuart Menefy <stuart.menefy@st.com>, Arnd Bergmann <arnd@arndb.de>,
        Rob Herring <robherring2@gmail.com>, Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v5] clocksource:arm_global_timer: Add ARM global timer
 support.
References: <1372089195-29219-1-git-send-email-srinivas.kandagatla@st.com> <51C8A6C8.8000009@codeaurora.org>
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On 24/06/13 21:06, Stephen Boyd wrote:
> On 06/24/13 08:53, Srinivas KANDAGATLA wrote:
>> +
>> +static void gt_clockevents_stop(struct clock_event_device *clk)
>> +{
>> +	gt_clockevent_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
>> +	disable_percpu_irq(clk->irq);
>> +}
>> +
>> +static int __cpuinit gt_clockevents_setup(struct clock_event_device *clk)
>> +{
>> +	struct clock_event_device *evt = this_cpu_ptr(gt_evt);
>> +	return evt->name ? 0 : gt_clockevents_init(evt);
>> +}
> 
> How does this work? gt_clockevents_stop() is using the
> clock_event_device struct from the ARM local timer layer whereas
> gt_clockevents_setup() is using a driver private allocation.
Thanks for pointing this..
This should fix it.

static void gt_clockevents_stop(struct clock_event_device *clk)
{
	struct clock_event_device *evt = this_cpu_ptr(gt_evt);
	gt_clockevent_set_mode(CLOCK_EVT_MODE_UNUSED, evt);
	disable_percpu_irq(evt->irq);
}

 Please just
> don't use the local timer API at all and use cpu notifiers instead.
Last time when I did try using cpu notifiers like arm_arch_timer, the
broadcast dummy timer did kick off and took over the local timer on the
secondary cpus. Resulting in lot of broadcast IPI's.

If I use cpu notifiers I will end up two clk events on a each core (one
dummy from arm/kernel/smp.c and other gt clk_evt). I think I can only
use cpu notifiers in my case once your patches are in.
Also I cant disable LOCAL_TIMERS as it y by default.

Am I missing something?

Am happy to move to cpu notifiers if it works, else the driver will be
broken.


Thanks,
srini
> 

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