Re: [PATCH] watchdog: meson: Fix the wrong value of left time

From: Neil Armstrong <narmstrong@baylibre.com>
To: Xingyu Chen <xingyu.chen@amlogic.com>,
	Wim Van Sebroeck <wim@linux-watchdog.org>,
	Guenter Roeck <linux@roeck-us.net>,
	Kevin Hilman <khilman@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
Subject: Re: [PATCH] watchdog: meson: Fix the wrong value of left time
Date: Mon, 30 Sep 2019 10:16:53 +0200	[thread overview]
Message-ID: <06f3e719-a6e1-ef70-0c5c-1a07f809905a@baylibre.com> (raw)
In-Reply-To: <1569754429-17287-1-git-send-email-xingyu.chen@amlogic.com>

On 29/09/2019 12:53, 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>
> ---
>  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 = {
> 

Acked-by: Neil Armstrong <narmstrong@baylibre.com>