linux-kernel - [PATCH v2 05/11] watchdog: rzg2l_wdt: Remove reset de-assert on probe/stop

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Message-Id: <20240131102017.1841495-6-claudiu.beznea.uj@bp.renesas.com>
Date: Wed, 31 Jan 2024 12:20:11 +0200
From: Claudiu <claudiu.beznea@...on.dev>
To: wim@...ux-watchdog.org,
	linux@...ck-us.net,
	robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org,
	conor+dt@...nel.org,
	geert+renesas@...der.be,
	magnus.damm@...il.com,
	mturquette@...libre.com,
	sboyd@...nel.org,
	p.zabel@...gutronix.de,
	biju.das.jz@...renesas.com
Cc: linux-watchdog@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-clk@...r.kernel.org,
	claudiu.beznea@...on.dev,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: [PATCH v2 05/11] watchdog: rzg2l_wdt: Remove reset de-assert on probe/stop

From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

There is no need to de-assert the reset signal on probe as the watchdog
is not used prior executing start. Also, the clocks are not enabled in
probe (pm_runtime_enable() doesn't do that), thus this is another indicator
that the watchdog wasn't used previously like this. Instead, keep the
watchdog hardware in its previous state at probe (by default it is in
reset state), enable it when it is started and move it to reset state
when it is stopped. This saves some extra power when the watchdog is
unused.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---

Changes in v2:
- none

 drivers/watchdog/rzg2l_wdt.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
index 7bce093316c4..93a49fd0c7aa 100644
--- a/drivers/watchdog/rzg2l_wdt.c
+++ b/drivers/watchdog/rzg2l_wdt.c
@@ -129,6 +129,10 @@ static int rzg2l_wdt_start(struct watchdog_device *wdev)
 	if (ret)
 		return ret;
 
+	ret = reset_control_deassert(priv->rstc);
+	if (ret)
+		return ret;
+
 	/* Initialize time out */
 	rzg2l_wdt_init_timeout(wdev);
 
@@ -146,7 +150,9 @@ static int rzg2l_wdt_stop(struct watchdog_device *wdev)
 	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
 	int ret;
 
-	rzg2l_wdt_reset(priv);
+	ret = reset_control_assert(priv->rstc);
+	if (ret)
+		return ret;
 
 	ret = pm_runtime_put(wdev->parent);
 	if (ret < 0)
@@ -186,6 +192,12 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev,
 	clk_prepare_enable(priv->osc_clk);
 
 	if (priv->devtype == WDT_RZG2L) {
+		int ret;
+
+		ret = reset_control_deassert(priv->rstc);
+		if (ret)
+			return ret;
+
 		/* Generate Reset (WDTRSTB) Signal on parity error */
 		rzg2l_wdt_write(priv, 0, PECR);
 
@@ -236,13 +248,11 @@ static const struct watchdog_ops rzg2l_wdt_ops = {
 	.restart = rzg2l_wdt_restart,
 };
 
-static void rzg2l_wdt_reset_assert_pm_disable(void *data)
+static void rzg2l_wdt_pm_disable(void *data)
 {
 	struct watchdog_device *wdev = data;
-	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
 
 	pm_runtime_disable(wdev->parent);
-	reset_control_assert(priv->rstc);
 }
 
 static int rzg2l_wdt_probe(struct platform_device *pdev)
@@ -285,10 +295,6 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
 		return dev_err_probe(&pdev->dev, PTR_ERR(priv->rstc),
 				     "failed to get cpg reset");
 
-	ret = reset_control_deassert(priv->rstc);
-	if (ret)
-		return dev_err_probe(dev, ret, "failed to deassert");
-
 	priv->devtype = (uintptr_t)of_device_get_match_data(dev);
 
 	if (priv->devtype == WDT_RZV2M) {
@@ -309,9 +315,7 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
 	priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
 
 	watchdog_set_drvdata(&priv->wdev, priv);
-	ret = devm_add_action_or_reset(&pdev->dev,
-				       rzg2l_wdt_reset_assert_pm_disable,
-				       &priv->wdev);
+	ret = devm_add_action_or_reset(&pdev->dev, rzg2l_wdt_pm_disable, &priv->wdev);
 	if (ret < 0)
 		return ret;
 
-- 
2.39.2