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

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Message-ID: <1627293708.10231.3.camel@mhfsdcap03>
Date:   Mon, 26 Jul 2021 18:01:48 +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>,
        <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

hi Daniel,

Gentle pin for this patch.

Thanks
Best Regards
Fengquan


On Wed, 2021-04-21 at 18:27 +0800, Fengquan Chen wrote:
> 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/
> > 
>