linux-kernel - [PATCH v6 7/8] watchdog: max77620: add comment to clarify set

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Message-Id: <20220223175908.191618-8-luca@lucaceresoli.net>
Date:   Wed, 23 Feb 2022 18:59:07 +0100
From:   Luca Ceresoli <luca@...aceresoli.net>
To:     linux-kernel@...r.kernel.org
Cc:     Luca Ceresoli <luca@...aceresoli.net>,
        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>,
        Guenter Roeck <linux@...ck-us.net>, devicetree@...r.kernel.org,
        linux-rtc@...r.kernel.org, linux-watchdog@...r.kernel.org
Subject: [PATCH v6 7/8] watchdog: max77620: add comment to clarify set_timeout procedure

Clarify why we need to ping the watchdog before changing the timeout by
quoting the MAX77714 datasheet.

Signed-off-by: Luca Ceresoli <luca@...aceresoli.net>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>

---

Changes in v6: none

Changes in v5:
 - improve comment to remove misleading ambiguous interpretation
   (Guenter Roeck)

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 cd321c7e0d59..b76ad6ba0915 100644
--- a/drivers/watchdog/max77620_wdt.c
+++ b/drivers/watchdog/max77620_wdt.c
@@ -123,6 +123,11 @@ 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 but applies to MAX77620 too)
+	 */
 	ret = regmap_update_bits(wdt->rmap, wdt->drv_data->reg_cnfg_glbl3,
 				 wdt->drv_data->wdtc_mask, 0x1);
 	if (ret < 0)
-- 
2.25.1