Subject: [PATCH 1/7] clocksource: mediatek: Don't run event_handler if it is NULL

From: [email-masked] (Daniel Lezcano)
Date: Mon, 04 May 2015 10:44:18 +0200

On 05/04/2015 10:34 AM, Matthias Brugger wrote:
> 2015-05-04 10:14 GMT+02:00 Daniel Lezcano <[email-masked]>:
>> 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 <[email-masked]>
>>> ---
>>>    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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