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

From: Fengquan Chen
Date: Wed Apr 21 2021 - 06:27:50 EST


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@xxxxxxxxxxxx>
> >
> > ---
> > 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/
>