linux-kernel - Re: [PATCH] watchdog: apple: Increase reset delay to 150ms

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Message-ID: <1081ea3e-73e7-4e98-9a2e-127238a9ed42@roeck-us.net>
Date: Fri, 13 Sep 2024 11:01:14 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Nick Chan <towinchenmi@...il.com>, Hector Martin <marcan@...can.st>,
 Sven Peter <sven@...npeter.dev>, Alyssa Rosenzweig <alyssa@...enzweig.io>,
 Wim Van Sebroeck <wim@...ux-watchdog.org>, asahi@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org, linux-watchdog@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: apple: Increase reset delay to 150ms

On 9/13/24 10:45, Nick Chan wrote:
> The Apple A8X SoC seems to be slowest at resetting, taking up to around
> 125ms to reset. Wait 150ms to be safe here.
> 
> Signed-off-by: Nick Chan <towinchenmi@...il.com>

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

> ---
>   drivers/watchdog/apple_wdt.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/apple_wdt.c b/drivers/watchdog/apple_wdt.c
> index d4f739932f0b..353ecf0b04dc 100644
> --- a/drivers/watchdog/apple_wdt.c
> +++ b/drivers/watchdog/apple_wdt.c
> @@ -127,11 +127,11 @@ static int apple_wdt_restart(struct watchdog_device *wdd, unsigned long mode,
>   	/*
>   	 * Flush writes and then wait for the SoC to reset. Even though the
>   	 * reset is queued almost immediately experiments have shown that it
> -	 * can take up to ~20-25ms until the SoC is actually reset. Just wait
> -	 * 50ms here to be safe.
> +	 * can take up to ~120-125ms until the SoC is actually reset. Just
> +	 * wait 150ms here to be safe.
>   	 */
>   	(void)readl_relaxed(wdt->regs + APPLE_WDT_WD1_CUR_TIME);
> -	mdelay(50);
> +	mdelay(150);
>   
>   	return 0;
>   }
> 
> base-commit: 5acd9952f95fb4b7da6d09a3be39195a80845eb6