From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: Evan Benn <evanbenn@gmail.com>
Cc: Evan Benn <evanbenn@chromium.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
Stanley Chu <stanley.chu@mediatek.com>,
Alexey Klimov <alexey.klimov@linaro.org>,
Julia Lawall <Julia.Lawall@lip6.fr>,
Yingjoe Chen <yingjoe.chen@mediatek.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-mediatek@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
Viresh Kumar <viresh.kumar@linaro.org>,
LKML <linux-kernel@vger.kernel.org>,
Fabien Parent <fparent@baylibre.com>
Subject: Re: [PATCH v2] drivers/clocksource/mediatek: Ack and disable interrupts on shutdown
Date: Fri, 2 Apr 2021 16:15:13 +0200 [thread overview]
Message-ID: <67eed9a2-2b97-be1b-3290-948da662ea65@linaro.org> (raw)
In-Reply-To: <CAP8nV8rv6bKARZ31fVqcjVgMe+5UyVG8UAyNsm1hDCP2BbRSgw@mail.gmail.com>
Hi Evan,
On 27/03/2021 02:31, Evan Benn wrote:
> Hi Daniel,
>
> That is a good point, and I did try that at first and it works fine. I
> uploaded this version because the suspend/resume callbacks were
> undocumented and mostly not used by other clocksource drivers. I
> thought a smaller diff might be preferable.
> I also thought it would be better to shut off the interrupt as soon as
> it is not needed, avoiding any other potential bugs, instead of just
> fixing the one we know about with suspend. I'm not sure how the other
> driver / timer disable flows are intended to work for example
> (shutdown, detach, etc).
>
> That said I am happy to upload that version if people think it is better.
IMO, it is not in the normal flow to disable/enable the interrupts.
Does this timer belong to an always-on power domain ?
> https://elixir.bootlin.com/linux/latest/source/include/linux/clockchips.h#L120
>
>
> On Thu, 25 Mar 2021 at 19:10, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
>>
>> 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@chromium.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);
>>>
>>
>>
>> --
>> <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
>>
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--
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Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
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next prev parent reply other threads:[~2021-04-02 14:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-25 1:35 [PATCH v2] drivers/clocksource/mediatek: Ack and disable interrupts on shutdown Evan Benn
2021-03-25 8:07 ` Daniel Lezcano
2021-03-27 1:31 ` Evan Benn
2021-04-02 14:15 ` Daniel Lezcano [this message]
2021-04-06 1:01 ` Evan Benn
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