linux-kernel - Re: [PATCH v4 8/9] watchdog: max77620: add comment to clarify set

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Message-ID: <20211129160414.GA3014810@roeck-us.net>
Date:   Mon, 29 Nov 2021 08:04:14 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Luca Ceresoli <luca@...aceresoli.net>
Cc:     linux-kernel@...r.kernel.org, Lee Jones <lee.jones@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        devicetree@...r.kernel.org, linux-rtc@...r.kernel.org,
        linux-watchdog@...r.kernel.org,
        Chiwoong Byun <woong.byun@...sung.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v4 8/9] watchdog: max77620: add comment to clarify
 set_timeout procedure

On Sat, Nov 20, 2021 at 04:57:06PM +0100, Luca Ceresoli wrote:
> Clarify why we need to ping the watchdog before changing the timeout by
> quoting the MAX77714 datasheet.
> 

Unless I am missing something, this adds confusion instead of clarifying
anything, and it is misleading. The added comment in the code makes it
sound like clearing the watchdog timer is only needed for MAX77614.
However, the code was in place for MAX77620, suggesting that it was needed
for that chip as well and is not MAX77614 specific.

Please either drop this patch or rephrase it to clarify that it applies
to both chips.

Guenter

> Signed-off-by: Luca Ceresoli <luca@...aceresoli.net>
> ---
> 
> This patch is new in v4. It adds a clarification comment to the max77620
> driver taken from v3 patch 7.
> ---
>  drivers/watchdog/max77620_wdt.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/watchdog/max77620_wdt.c b/drivers/watchdog/max77620_wdt.c
> index 06b48295fab6..f082a4ea2c03 100644
> --- a/drivers/watchdog/max77620_wdt.c
> +++ b/drivers/watchdog/max77620_wdt.c
> @@ -132,6 +132,11 @@ static int max77620_wdt_set_timeout(struct watchdog_device *wdt_dev,
>  		break;
>  	}
>  
> +	/*
> +	 * "If the value of TWD needs to be changed, clear the system
> +	 * watchdog timer first [...], then change the value of TWD."
> +	 * (MAX77714 datasheet)
> +	 */
>  	ret = regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl3,
>  				 wdt->drv_data->wdtc_mask, 0x1);
>  	if (ret < 0)