linux-kernel - Re: [PATCH] [v4, 1/1] clocksource/drivers/timer-mediatek: optimize systimer irq clear flow on shutdown

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Date:   Wed, 21 Apr 2021 18:27:28 +0800
From:   Fengquan Chen <fengquan.chen@...iatek.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <dehui.sun@...iatek.com>, Evan Benn <evanbenn@...omium.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH] [v4, 1/1] clocksource/drivers/timer-mediatek: optimize
 systimer irq clear flow on shutdown

On Mon, 2021-04-19 at 10:44 +0200, Daniel Lezcano wrote:
> On 09/04/2021 11:22, Fengquan Chen wrote:
> > mtk_syst_clkevt_shutdown is called after irq disabled in suspend flow,
> > clear any pending systimer irq when shutdown to avoid suspend aborted
> > due to timer irq pending
> > 
> > Also as for systimer in mediatek socs, there must be firstly enable
> > timer before clear systimer irq
> > 
> > Fixes: e3af677607d9("clocksource/drivers/timer-mediatek: Add support for system timer")
> > Signed-off-by: Fengquan Chen <fengquan.chen@...iatek.com>
> > 
> > ---
> >  drivers/clocksource/timer-mediatek.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/clocksource/timer-mediatek.c b/drivers/clocksource/timer-mediatek.c
> > index 9318edc..6461fd3 100644
> > --- a/drivers/clocksource/timer-mediatek.c
> > +++ b/drivers/clocksource/timer-mediatek.c
> > @@ -60,9 +60,9 @@
> >   * SYST_CON_EN: Clock enable. Shall be set to
> >   *   - Start timer countdown.
> >   *   - Allow timeout ticks being updated.
> > - *   - Allow changing interrupt functions.
> > + *   - Allow changing interrupt status,like clear irq pending.
> >   *
> > - * SYST_CON_IRQ_EN: Set to allow interrupt.
> > + * SYST_CON_IRQ_EN: Set to enable interrupt.
> >   *
> >   * SYST_CON_IRQ_CLR: Set to clear interrupt.
> >   */
> > @@ -75,6 +75,7 @@
> >  static void mtk_syst_ack_irq(struct timer_of *to)
> >  {
> >  	/* Clear and disable interrupt */
> > +	writel(SYST_CON_EN, SYST_CON_REG(to));
> >  	writel(SYST_CON_IRQ_CLR | SYST_CON_EN, SYST_CON_REG(to));
> >  }
> 
> IIRC, there is a hardware issue here. If it is the case, please describe
> it and refer to an errata if any.

Thanks for review.
here is just a hw config flow limitation, not a bug.

> 
> Also Evan Benn commented your code and asked a couple of questions [1],
> please answer before reposting a new version.
> 
> Comments ignored == patch ignored

Thanks. i have answered by mail before, but it didn't uploaded to the
list. has been uploaded ok now.

> 
> > @@ -111,6 +112,9 @@ static int mtk_syst_clkevt_next_event(unsigned long ticks,
> >  
> >  static int mtk_syst_clkevt_shutdown(struct clock_event_device *clkevt)
> >  {
> > +	/* Clear any irq */
> > +	mtk_syst_ack_irq(to_timer_of(clkevt));
> > +
> >  	/* Disable timer */
> >  	writel(0, SYST_CON_REG(to_timer_of(clkevt)));
> 
> Please check out the patch sent by Evan Benn [2], if you agree, ack it.
> 

Thanks

agree

> Thanks
> 
>   -- Daniel
> 
> [1] https://patchwork.kernel.org/comment/24059277/
> [2]
> https://lore.kernel.org/linux-arm-kernel/20210412132200.v3.1.I1d9917047de06715da16e1620759f703fcfdcbcb@changeid/
>