From: Guenter Roeck <linux@roeck-us.net>
To: Judith Mendez <jm@ti.com>
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>,
linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] watchdog: rti_wdt: Set min_hw_heartbeat_ms to accommodate 5% safety margin
Date: Sat, 6 Apr 2024 05:56:27 -0700 [thread overview]
Message-ID: <717195a8-84f7-4bdc-a108-efafd3ef2a46@roeck-us.net> (raw)
In-Reply-To: <20240403212426.582727-1-jm@ti.com>
On Wed, Apr 03, 2024 at 04:24:26PM -0500, Judith Mendez wrote:
> On AM62x, the watchdog is pet before the valid window
> is open. Fix min_hw_heartbeat and accommodate a 5% safety
> margin with the exception of open window size < 10%,
> which shall use <5% due to the smaller open window size.
>
> Signed-off-by: Judith Mendez <jm@ti.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> ---
> drivers/watchdog/rti_wdt.c | 24 +++++++++++++-----------
> 1 file changed, 13 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
> index 8e1be7ba0103..0b16ada659cc 100644
> --- a/drivers/watchdog/rti_wdt.c
> +++ b/drivers/watchdog/rti_wdt.c
> @@ -92,7 +92,7 @@ static int rti_wdt_start(struct watchdog_device *wdd)
> * to be 50% or less than that; we obviouly want to configure the open
> * window as large as possible so we select the 50% option.
> */
> - wdd->min_hw_heartbeat_ms = 500 * wdd->timeout;
> + wdd->min_hw_heartbeat_ms = 550 * wdd->timeout;
>
> /* Generate NMI when wdt expires */
> writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
> @@ -126,31 +126,33 @@ static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
> * be petted during the open window; not too early or not too late.
> * The HW configuration options only allow for the open window size
> * to be 50% or less than that.
> + * To avoid any glitches, we accommodate 5% safety margin, with the
> + * exception of open window size < 10%.
> */
> switch (wsize) {
> case RTIWWDSIZE_50P:
> - /* 50% open window => 50% min heartbeat */
> - wdd->min_hw_heartbeat_ms = 500 * heartbeat;
> + /* 50% open window => 55% min heartbeat */
> + wdd->min_hw_heartbeat_ms = 550 * heartbeat;
> break;
>
> case RTIWWDSIZE_25P:
> - /* 25% open window => 75% min heartbeat */
> - wdd->min_hw_heartbeat_ms = 750 * heartbeat;
> + /* 25% open window => 80% min heartbeat */
> + wdd->min_hw_heartbeat_ms = 800 * heartbeat;
> break;
>
> case RTIWWDSIZE_12P5:
> - /* 12.5% open window => 87.5% min heartbeat */
> - wdd->min_hw_heartbeat_ms = 875 * heartbeat;
> + /* 12.5% open window => 92.5% min heartbeat */
> + wdd->min_hw_heartbeat_ms = 925 * heartbeat;
> break;
>
> case RTIWWDSIZE_6P25:
> - /* 6.5% open window => 93.5% min heartbeat */
> - wdd->min_hw_heartbeat_ms = 935 * heartbeat;
> + /* 6.5% open window => 96.5% min heartbeat */
> + wdd->min_hw_heartbeat_ms = 965 * heartbeat;
> break;
>
> case RTIWWDSIZE_3P125:
> - /* 3.125% open window => 96.9% min heartbeat */
> - wdd->min_hw_heartbeat_ms = 969 * heartbeat;
> + /* 3.125% open window => 97.9% min heartbeat */
> + wdd->min_hw_heartbeat_ms = 979 * heartbeat;
> break;
>
> default:
> --
> 2.43.2
>
>
prev parent reply other threads:[~2024-04-06 12:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-03 21:24 [PATCH] watchdog: rti_wdt: Set min_hw_heartbeat_ms to accommodate 5% safety margin Judith Mendez
2024-04-04 8:28 ` Francesco Dolcini
2024-04-04 15:32 ` Judith Mendez
2024-04-05 12:37 ` Rafael Beims
2024-04-06 12:56 ` Guenter Roeck [this message]
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