Message-ID: <55473162.5010608@linaro.org>
Date: Mon, 04 May 2015 10:44:18 +0200
From: Daniel Lezcano <daniel.lezcano@linaro.org>
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To: Matthias Brugger <matthias.bgg@gmail.com>
CC: Yingjoe Chen <yingjoe.chen@mediatek.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>, Arnd Bergmann <arnd@arndb.de>,
        Olof Johansson <olof@lixom.net>, Rob Herring <robh+dt@kernel.org>,
        Pawel Moll <pawel.moll@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Russell King <linux@arm.linux.org.uk>,
        Jason Cooper <jason@lakedaemon.net>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Marc Carino <marc.ceeeee@gmail.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        linux-mediatek@lists.infradead.org,
        srv_heupstream <srv_heupstream@mediatek.com>,
        Sascha Hauer <kernel@pengutronix.de>
Subject: Re: [PATCH 1/7] clocksource: mediatek: Don't run event_handler if
 it is NULL
References: <1430466210-22963-1-git-send-email-yingjoe.chen@mediatek.com>	<1430466210-22963-2-git-send-email-yingjoe.chen@mediatek.com>	<55472A80.9020904@linaro.org> <CABuKBeKBcg+zCDSx8PNCsRC3A8Lo9ripw5ZYCC0c+GjJN8dp6Q@mail.gmail.com>
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On 05/04/2015 10:34 AM, Matthias Brugger wrote:
> 2015-05-04 10:14 GMT+02:00 Daniel Lezcano <daniel.lezcano@linaro.org>:
>> On 05/01/2015 09:43 AM, Yingjoe Chen wrote:
>>>
>>> Spurious timer interrupt is noticed in mtk timer and cause kernel
>>> crash. In mtk_timer_interrupt(), only run event_handler if it is
>>> not NULL.
>>>
>>> Signed-off-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
>>> ---
>>>    drivers/clocksource/mtk_timer.c | 3 ++-
>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/clocksource/mtk_timer.c
>>> b/drivers/clocksource/mtk_timer.c
>>> index 68ab423..85e0ab5 100644
>>> --- a/drivers/clocksource/mtk_timer.c
>>> +++ b/drivers/clocksource/mtk_timer.c
>>> @@ -143,7 +143,8 @@ static irqreturn_t mtk_timer_interrupt(int irq, void
>>> *dev_id)
>>>
>>>          /* Acknowledge timer0 irq */
>>>          writel(GPT_IRQ_ACK(GPT_CLK_EVT), evt->gpt_base + GPT_IRQ_ACK_REG);
>>> -       evt->dev.event_handler(&evt->dev);
>>> +       if (evt->dev.event_handler)
>>> +               evt->dev.event_handler(&evt->dev);
>>>
>>>          return IRQ_HANDLED;
>>>    }
>>>
>>
>> This fix does not look good.
>>
>> Could you try by requesting the irq *after* clockevents_config_and_register
>> in the init sequence [1] ?
>>
>
>  From my understanding [1] should already fix this.
>
> [1] https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/drivers/clocksource/mtk_timer.c?id=d4a19eb3b15a4ba98f627182f48d5bc0cffae670

Indeed it seems to fix it. But I think request_irq should be done after 
clockevents_config_and_register in any case.

Yingjoe, are the spurious interrupts occurring with the fix Matthias 
mentions ?


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