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Subject: Re: [PATCH] watchdog: meson: Fix the wrong value of left time
To:     Xingyu Chen <xingyu.chen@amlogic.com>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Kevin Hilman <khilman@baylibre.com>,
        Neil Armstrong <narmstrong@baylibre.com>
Cc:     Jerome Brunet <jbrunet@baylibre.com>,
        Qianggui Song <qianggui.song@amlogic.com>,
        Jianxin Pan <jianxin.pan@amlogic.com>,
        linux-watchdog@vger.kernel.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <1569754429-17287-1-git-send-email-xingyu.chen@amlogic.com>
From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <ee3ea7d5-1adf-c718-4533-70b04bb23ecc@roeck-us.net>
Date:   Mon, 30 Sep 2019 06:12:51 -0700
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On 9/29/19 3:53 AM, Xingyu Chen wrote:
> The left time value is wrong when we get it by sysfs. The left time value
> should be equal to preset timeout value minus elapsed time value. According
> to the Meson-GXB/GXL datasheets which can be found at [0], the timeout value
> is saved to BIT[0-15] of the WATCHDOG_TCNT, and elapsed time value is saved
> to BIT[16-31] of the WATCHDOG_TCNT.
> 
> [0]: http://linux-meson.com
> 
> Fixes: 683fa50f0e18 ("watchdog: Add Meson GXBB Watchdog Driver")
> Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>   drivers/watchdog/meson_gxbb_wdt.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/meson_gxbb_wdt.c b/drivers/watchdog/meson_gxbb_wdt.c
> index d17c1a6..5a9ca10 100644
> --- a/drivers/watchdog/meson_gxbb_wdt.c
> +++ b/drivers/watchdog/meson_gxbb_wdt.c
> @@ -89,8 +89,8 @@ static unsigned int meson_gxbb_wdt_get_timeleft(struct watchdog_device *wdt_dev)
>   
>   	reg = readl(data->reg_base + GXBB_WDT_TCNT_REG);
>   
> -	return ((reg >> GXBB_WDT_TCNT_CNT_SHIFT) -
> -		(reg & GXBB_WDT_TCNT_SETUP_MASK)) / 1000;
> +	return ((reg & GXBB_WDT_TCNT_SETUP_MASK) -
> +		(reg >> GXBB_WDT_TCNT_CNT_SHIFT)) / 1000;
>   }
>   
>   static const struct watchdog_ops meson_gxbb_wdt_ops = {
>