Hi, Guenter Roeck :

Thanks for your review. Sorry I was so focused on fixing code and 
I forgot to respond to the email. I modify the code as you comment
and answer the question.

Thanks
Best Regards,
Xiantao Hu

-----Original Message-----
From: Guenter Roeck [mailto:groeck7@gmail.com] On Behalf Of Guenter Roeck
Sent: Friday, November 12, 2021 10:46 PM
To: xt.hu[胡先韬] <xt.hu@cqplus1.com>; wim@linux-watchdog.org; p.zabel@pengutronix.de;
linux-kernel@vger.kernel.org; linux-watchdog@vger.kernel.org; robh+dt@kernel.org;
devicetree@vger.kernel.org
Cc: Wells Lu 呂芳騰 <redacted>; qinjian[覃健] <qinjian@cqplus1.com>
Subject: Re: [PATCH 1/2] watchdog: Add watchdog driver for Sunplus SP7021

On 11/12/21 2:59 AM, Xiantao Hu wrote:

quoted

Sunplus SP7021 requires watchdog timer support.
Add watchdog driver to enable this.

Signed-off-by: Xiantao Hu <xt.hu@cqplus1.com>

...

quoted

+struct sp_wdt_priv {
+	struct watchdog_device wdev;
+	void __iomem *base;
+	void __iomem *miscellaneous;

Please find a better name for this variable. Also, unless I am
missing something, it is only used in the init function. That means
it can be passed to that function as parameter and doesn't need
to be stored in sp_wdt_priv.

I will remove the miscellaneous from sp_wdt_priv and pass
to that function as parameter.

quoted

+	struct clk *clk;
+	struct reset_control *rstc;
+};

...

quoted

+static int sp_wdt_set_timeout(struct watchdog_device *wdev,
+				   unsigned int timeout)
+{
+	wdev->timeout = timeout;
+

I would assume this also needs to set the new timeout in HW if
the watchdog is running, or the watchdog could time out before
userspace sends another ping.

I will call the ping() after assigning timeout.

quoted

+	return 0;
+}
+

...

quoted

+
+static int sp_wdt_start(struct watchdog_device *wdev)
+{
+	int ret;
+
+	ret = sp_wdt_set_timeout(wdev, wdev->timeout);

That function never returns an error, so checking for it is
pointless here.

I will remove the variable ret.

quoted

+	if (ret < 0)
+		return ret;
+

...

quoted

+/*
+ * 1.We need to reset watchdog flag(clear watchdog interrupt) here
+ * because watchdog timer driver does not have an interrupt handler,
+ * and before enalbe STC and RBUS watchdog timeout. Otherwise,

enable

I will fix it.

quoted

+ * the intr is always in the triggered state.
+ * 2.enable STC and RBUS watchdog timeout trigger.
+ * 3.watchdog conuter is running, need to be stopped.

counter

I will fix it.

quoted

+ */

...

quoted

+
+	wdt_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	priv->miscellaneous =
+	    devm_ioremap(dev, wdt_res->start, resource_size(wdt_res));

Why not use devm_ioremap_resource() ? Or, for that matter,
devm_platform_ioremap_resource() like above ?

The function of this register is miscellaneous. The register 
accessed here shared by multiple drivers. Use the function 
of devm_platform_ioremap_resource() which internally
call request_mem_region() causes an error. So I handle it 
in this way. Any better ways?

quoted

+	if (IS_ERR(priv->miscellaneous))
+		return PTR_ERR(priv->miscellaneous);
+
+	priv->wdev.info = &sp_wdt_info;
+	priv->wdev.ops = &sp_wdt_ops;
+	priv->wdev.timeout = SP_WDT_MAX_TIMEOUT;
+	priv->wdev.max_timeout = SP_WDT_MAX_TIMEOUT;
+	priv->wdev.min_timeout = SP_WDT_MIN_TIMEOUT;

THis should really use max_hw_heartbeat_ms to let the core
ping the watchdog if larger timeouts are desired.

I will add the max_hw_heartbeat_ms and modify the 
ping ().

quoted

+	priv->wdev.parent = dev;
+
+	watchdog_set_drvdata(&priv->wdev, priv);
+	sp_wdt_hw_init(&priv->wdev);
+
+	watchdog_init_timeout(&priv->wdev, timeout, dev);
+	watchdog_set_nowayout(&priv->wdev, nowayout);
+	watchdog_stop_on_reboot(&priv->wdev);
+
+	err = devm_watchdog_register_device(dev, &priv->wdev);

Since you call watchdog_unregister_device() below you can not use
the devm_ function here.

I will drop the function remove() and not call watchdog_unregister_device() .
Use the devm_add_action_or_reset() add reset_control_assert() and
clk_disable_unprepare().

quoted

+	if (unlikely(err))

This is not time critical. Drop the unlikely.

I will fix it.

quoted

+		return err;
+
+	dev_info(dev, "Watchdog enabled (timeout=%d sec%s.)\n",
+		 priv->wdev.timeout, nowayout ? ", nowayout" : "");
+
+	return 0;
+}
+
+static int sp_wdt_remove(struct platform_device *pdev)
+{
+	struct sp_wdt_priv *priv = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&priv->wdev);
+
+	reset_control_assert(priv->rstc);
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+

...

quoted

+
+static int __maybe_unused sp_wdt_resume(struct device *dev)
+{
+	struct sp_wdt_priv *priv = dev_get_drvdata(dev);
+
+	if (watchdog_active(&priv->wdev))
+		sp_wdt_start(&priv->wdev);
+

Shouldn't the order be the opposite of the order in the suspend function ?

 
I will fix it.

quoted

+	reset_control_deassert(priv->rstc);
+	clk_prepare_enable(priv->clk);
+
+	return 0;
+}

...

quoted