Re: [PATCH 2/3] watchdog: xilinx_wwdt: Add Versal window watchdog support

[Guenter Roeck]

On 9/30/22 03:35, Krzysztof Kozlowski wrote:
> On 27/09/2022 13:02, Srinivas Neeli wrote:
> > +
> > +static void xwwdt_clk_disable_unprepare(void *data)
> > +{
> > +	clk_disable_unprepare(data);
>
> If watchdog is stopped and then device unbound, don't you have double
> disable? IOW, where is matching clk_enable?

After looking into the entire driver code, I see the problem:
clk_disable() is called in the stop function. That is wrong;
if the clock is disabled in the stop function, it needs to be
enabled in the start function (which is not currently the case).
In that situation, using the devm_ callback when unloading the
driver isn't possible (or, rather, would require checking if the
clock is enabled before disabling it).

Thanks,
Guenter

> > +}
> > +
> > +static const struct watchdog_info xilinx_wwdt_ident = {
> > +	.options = WDIOF_KEEPALIVEPING |
> > +		WDIOF_SETTIMEOUT,
> > +	.firmware_version = 1,
> > +	.identity = "xlnx_window watchdog",
> > +};
> > +
> > +static const struct watchdog_ops xilinx_wwdt_ops = {
> > +	.owner = THIS_MODULE,
> > +	.start = xilinx_wwdt_start,
> > +	.stop = xilinx_wwdt_stop,
> > +	.set_timeout = xilinx_wwdt_set_timeout,
> > +	.ping = xilinx_wwdt_keepalive,
> > +};
> > +
> > +static int xwwdt_probe(struct platform_device *pdev)
> > +{
> > +	struct watchdog_device *xilinx_wwdt_wdd;
> > +	struct device *dev = &pdev->dev;
> > +	struct xwwdt_device *xdev;
> > +	int ret;
> > +
> > +	xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
> > +	if (!xdev)
> > +		return -ENOMEM;
> > +
> > +	xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
> > +	xilinx_wwdt_wdd->info = &xilinx_wwdt_ident;
> > +	xilinx_wwdt_wdd->ops = &xilinx_wwdt_ops;
> > +	xilinx_wwdt_wdd->parent = dev;
> > +
> > +	xdev->base = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(xdev->base))
> > +		return PTR_ERR(xdev->base);
> > +
> > +	xdev->clk = devm_clk_get(dev, NULL);
> > +	if (IS_ERR(xdev->clk))
> > +		return PTR_ERR(xdev->clk);
> > +
> > +	xdev->freq = clk_get_rate(xdev->clk);
> > +	if (!xdev->freq)
> > +		return -EINVAL;
> > +
> > +	ret = clk_prepare_enable(xdev->clk);
> > +	if (ret) {
> > +		dev_err(dev, "unable to enable clock\n");
> > +		return ret;
> > +	}
> > +
> > +	ret = devm_add_action_or_reset(dev, xwwdt_clk_disable_unprepare,
> > +				       xdev->clk);
> > +	if (ret)
> > +		return ret;
> > +
> > +	xilinx_wwdt_wdd->timeout = XWWDT_DEFAULT_TIMEOUT;
> > +	xilinx_wwdt_wdd->min_timeout = XWWDT_MIN_TIMEOUT;
> > +	xilinx_wwdt_wdd->max_timeout = XWWDT_MAX_TIMEOUT;
> > +
> > +	ret = watchdog_init_timeout(xilinx_wwdt_wdd,
> > +				    xwwdt_timeout, &pdev->dev);
> > +	if (ret)
> > +		dev_info(&pdev->dev, "Configured default timeout value\n");
> > +
> > +	spin_lock_init(&xdev->spinlock);
> > +	watchdog_set_drvdata(xilinx_wwdt_wdd, xdev);
> > +
> > +	ret = devm_watchdog_register_device(dev, xilinx_wwdt_wdd);
> > +	if (ret)
> > +		return ret;
> > +
> > +	dev_info(dev, "Xilinx window watchdog Timer with timeout %ds\n",
> > +		 xilinx_wwdt_wdd->timeout);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id xwwdt_of_match[] = {
> > +	{ .compatible = "xlnx,versal-wwdt-1.0", },
> > +	{},
> > +};
> > +MODULE_DEVICE_TABLE(of, xwwdt_of_match);
> > +
> > +static struct platform_driver xwwdt_driver = {
> > +	.probe = xwwdt_probe,
> > +	.driver = {
> > +		.name = "Xilinx window watchdog",
>
> Do you see spaces in other names of drivers?
>
> Best regards,
> Krzysztof