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From:   Avi Fishman <avifishman70@gmail.com>
Date:   Mon, 29 Jul 2019 19:52:39 +0300
Message-ID: <CAKKbWA6K4=qL7i5i2_jhB7KHBX3D+YsREP7yECdgD4j6VZFrLg@mail.gmail.com>
Subject: Re: [PATCH] [v4] clocksource/drivers/npcm: fix GENMASK and timer operation
To:     Tomer Maimon <tmaimon77@gmail.com>,
        Tali Perry <tali.perry1@gmail.com>,
        Patrick Venture <venture@google.com>,
        Nancy Yuen <yuenn@google.com>,
        Benjamin Fair <benjaminfair@google.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Avi Fishman <avifishman70@gmail.com>
Cc:     OpenBMC Maillist <openbmc@lists.ozlabs.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Please discard this. my mail tool corruppted it again.

On Mon, Jul 29, 2019 at 7:50 PM Avi Fishman <avifishman70@gmail.com> 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@gmail.com>
> ---
>  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;
> --
> 2.18.0


-- 
Regards,
Avi