linux-kernel - Re: [PATCH] [v5] clocksource/drivers/npcm: fix GENMASK and timer operation

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Date:   Wed, 21 Aug 2019 13:42:27 +0300
From:   Avi Fishman <avifishman70@...il.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     Tomer Maimon <tmaimon77@...il.com>,
        Tali Perry <tali.perry1@...il.com>,
        Patrick Venture <venture@...gle.com>,
        Nancy Yuen <yuenn@...gle.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [v5] clocksource/drivers/npcm: fix GENMASK and timer operation

Thanks Daniel,

It seems more clear now :)

Good to know about the need for Fixes tag.

On Wed, Aug 21, 2019 at 1:11 PM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> On 29/07/2019 19:03, Avi Fishman wrote:
> > NPCM7XX_Tx_OPER GENMASK bits where wrong,
> > Since NPCM7XX_REG_TICR0 register reset value of those bits was 0,
> > it did not cause an issue.
> > in npcm7xx_timer_oneshot() the original NPCM7XX_REG_TCSR0 register was
> > read again after masking it with ~NPCM7XX_Tx_OPER so the masking didn't
> > take effect.
> >
> > npcm7xx_timer_periodic() was not wrong but it wrote to NPCM7XX_REG_TICR0
> > in a middle of read modify write to NPCM7XX_REG_TCSR0 which is
> > confusing.
> > npcm7xx_timer_oneshot() did wrong calculation
> >
> > Signed-off-by: Avi Fishman <avifishman70@...il.com>
>
> I've applied the patch and massaged the changelog [1].
>
> Let me know if you disagree with it.
>
> Please, in the future take care of adding the Fixes tag.
>
> Thanks
>
>   -- Daniel
>
> [1]
> https://git.linaro.org/people/daniel.lezcano/linux.git/commit/?h=clockevents/next&id=a5f6679fc81e42fcbef0184770d8a3b04c0f153e
>
> > ---
> >  drivers/clocksource/timer-npcm7xx.c | 9 +++------
> >  1 file changed, 3 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/clocksource/timer-npcm7xx.c b/drivers/clocksource/timer-npcm7xx.c
> > index 8a30da7f083b..9780ffd8010e 100644
> > --- a/drivers/clocksource/timer-npcm7xx.c
> > +++ b/drivers/clocksource/timer-npcm7xx.c
> > @@ -32,7 +32,7 @@
> >  #define NPCM7XX_Tx_INTEN             BIT(29)
> >  #define NPCM7XX_Tx_COUNTEN           BIT(30)
> >  #define NPCM7XX_Tx_ONESHOT           0x0
> > -#define NPCM7XX_Tx_OPER                      GENMASK(27, 3)
> > +#define NPCM7XX_Tx_OPER                      GENMASK(28, 27)
> >  #define NPCM7XX_Tx_MIN_PRESCALE              0x1
> >  #define NPCM7XX_Tx_TDR_MASK_BITS     24
> >  #define NPCM7XX_Tx_MAX_CNT           0xFFFFFF
> > @@ -84,8 +84,6 @@ static int npcm7xx_timer_oneshot(struct clock_event_device *evt)
> >
> >       val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
> >       val &= ~NPCM7XX_Tx_OPER;
> > -
> > -     val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
> >       val |= NPCM7XX_START_ONESHOT_Tx;
> >       writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
> >
> > @@ -97,12 +95,11 @@ static int npcm7xx_timer_periodic(struct clock_event_device *evt)
> >       struct timer_of *to = to_timer_of(evt);
> >       u32 val;
> >
> > +     writel(timer_of_period(to), timer_of_base(to) + NPCM7XX_REG_TICR0);
> > +
> >       val = readl(timer_of_base(to) + NPCM7XX_REG_TCSR0);
> >       val &= ~NPCM7XX_Tx_OPER;
> > -
> > -     writel(timer_of_period(to), timer_of_base(to) + NPCM7XX_REG_TICR0);
> >       val |= NPCM7XX_START_PERIODIC_Tx;
> > -
> >       writel(val, timer_of_base(to) + NPCM7XX_REG_TCSR0);
> >
> >       return 0;
> >
>
>
> --
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-- 
Regards,
Avi