linux-kernel - Re: [PATCH v2] drivers/clocksource/mediatek: Ack and disable interrupts on shutdown

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Message-ID: <049946ac-5263-21ee-9651-7295f0bcf387@linaro.org>
Date:   Thu, 25 Mar 2021 09:07:48 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Evan Benn <evanbenn@...omium.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     Stanley Chu <stanley.chu@...iatek.com>,
        Alexey Klimov <alexey.klimov@...aro.org>,
        Julia Lawall <Julia.Lawall@...6.fr>,
        Yingjoe Chen <yingjoe.chen@...iatek.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        Viresh Kumar <viresh.kumar@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Fabien Parent <fparent@...libre.com>
Subject: Re: [PATCH v2] drivers/clocksource/mediatek: Ack and disable
 interrupts on shutdown

On 25/03/2021 02:35, Evan Benn wrote:
> set_state_shutdown is called during system suspend after interrupts have
> been disabled. If the timer has fired in the meantime, there will be
> a pending IRQ. So we ack that now and disable the timer. Without this
> ARM trusted firmware will abort the suspend due to the pending
> interrupt.
> 
> Now always disable the IRQ in state transitions, and re-enable in
> set_periodic and next_event.

Why not put add the suspend/resume callbacks and put there the specific
code and let the irq untouched in the normal flow ?

> Signed-off-by: Evan Benn <evanbenn@...omium.org>
> ---
> 
> Changes in v2:
> Remove the patch that splits the drivers into 2 files.
> 
>  drivers/clocksource/timer-mediatek.c | 49 +++++++++++++++++-----------
>  1 file changed, 30 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-mediatek.c b/drivers/clocksource/timer-mediatek.c
> index 9318edcd8963..fba2f9494d90 100644
> --- a/drivers/clocksource/timer-mediatek.c
> +++ b/drivers/clocksource/timer-mediatek.c
> @@ -132,13 +132,33 @@ static u64 notrace mtk_gpt_read_sched_clock(void)
>  	return readl_relaxed(gpt_sched_reg);
>  }
>  
> +static void mtk_gpt_disable_ack_interrupts(struct timer_of *to, u8 timer)
> +{
> +	u32 val;
> +
> +	/* Disable interrupts */
> +	val = readl(timer_of_base(to) + GPT_IRQ_EN_REG);
> +	writel(val & ~GPT_IRQ_ENABLE(timer), timer_of_base(to) +
> +	       GPT_IRQ_EN_REG);
> +
> +	/* Ack interrupts */
> +	writel(GPT_IRQ_ACK(timer), timer_of_base(to) + GPT_IRQ_ACK_REG);
> +}
> +
>  static void mtk_gpt_clkevt_time_stop(struct timer_of *to, u8 timer)
>  {
>  	u32 val;
>  
> +	/* Disable timer */
>  	val = readl(timer_of_base(to) + GPT_CTRL_REG(timer));
>  	writel(val & ~GPT_CTRL_ENABLE, timer_of_base(to) +
>  	       GPT_CTRL_REG(timer));
> +
> +	/* This may be called with interrupts disabled,
> +	 * so we need to ack any interrupt that is pending
> +	 * Or for example ATF will prevent a suspend from completing.
> +	 */
> +	mtk_gpt_disable_ack_interrupts(to, timer);
>  }
>  
>  static void mtk_gpt_clkevt_time_setup(struct timer_of *to,
> @@ -152,8 +172,10 @@ static void mtk_gpt_clkevt_time_start(struct timer_of *to,
>  {
>  	u32 val;
>  
> -	/* Acknowledge interrupt */
> -	writel(GPT_IRQ_ACK(timer), timer_of_base(to) + GPT_IRQ_ACK_REG);
> +	/* Enable interrupts */
> +	val = readl(timer_of_base(to) + GPT_IRQ_EN_REG);
> +	writel(val | GPT_IRQ_ENABLE(timer),
> +	       timer_of_base(to) + GPT_IRQ_EN_REG);
>  
>  	val = readl(timer_of_base(to) + GPT_CTRL_REG(timer));
>  
> @@ -226,21 +248,6 @@ __init mtk_gpt_setup(struct timer_of *to, u8 timer, u8 option)
>  	       timer_of_base(to) + GPT_CTRL_REG(timer));
>  }
>  
> -static void mtk_gpt_enable_irq(struct timer_of *to, u8 timer)
> -{
> -	u32 val;
> -
> -	/* Disable all interrupts */
> -	writel(0x0, timer_of_base(to) + GPT_IRQ_EN_REG);
> -
> -	/* Acknowledge all spurious pending interrupts */
> -	writel(0x3f, timer_of_base(to) + GPT_IRQ_ACK_REG);
> -
> -	val = readl(timer_of_base(to) + GPT_IRQ_EN_REG);
> -	writel(val | GPT_IRQ_ENABLE(timer),
> -	       timer_of_base(to) + GPT_IRQ_EN_REG);
> -}
> -
>  static struct timer_of to = {
>  	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
>  
> @@ -292,6 +299,12 @@ static int __init mtk_gpt_init(struct device_node *node)
>  	if (ret)
>  		return ret;
>  
> +	/* In case the firmware left the interrupts enabled
> +	 * disable and ack those now
> +	 */
> +	mtk_gpt_disable_ack_interrupts(&to, TIMER_CLK_SRC);
> +	mtk_gpt_disable_ack_interrupts(&to, TIMER_CLK_EVT);
> +
>  	/* Configure clock source */
>  	mtk_gpt_setup(&to, TIMER_CLK_SRC, GPT_CTRL_OP_FREERUN);
>  	clocksource_mmio_init(timer_of_base(&to) + GPT_CNT_REG(TIMER_CLK_SRC),
> @@ -305,8 +318,6 @@ static int __init mtk_gpt_init(struct device_node *node)
>  	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
>  					TIMER_SYNC_TICKS, 0xffffffff);
>  
> -	mtk_gpt_enable_irq(&to, TIMER_CLK_EVT);
> -
>  	return 0;
>  }
>  TIMER_OF_DECLARE(mtk_mt6577, "mediatek,mt6577-timer", mtk_gpt_init);
> 


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