linux-kernel - Re: [PATCH] watchdog: of_xilinx_wdt: Remove unnecessary clock disable call in the remove path

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Message-ID: <09d7be2d-c3ee-286c-7035-5a253d033278@roeck-us.net>
Date:   Mon, 28 Aug 2023 02:37:36 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Srinivas Neeli <srinivas.neeli@....com>,
        shubhrajyoti.datta@....com, michal.simek@....com,
        wim@...ux-watchdog.org, linux@...ck-us.ne,
        christophe.jaillet@...adoo.fr
Cc:     linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        git@....com, neelisrinivas18@...il.com
Subject: Re: [PATCH] watchdog: of_xilinx_wdt: Remove unnecessary clock disable
 call in the remove path

On 8/28/23 02:20, Srinivas Neeli wrote:
> There is a mismatch in axi clock enable and disable calls.
> The axi clock is enabled and disabled by the probe function,
> then it is again disabled in the remove path.
> So observed the call trace while removing the module.
> Use the clk_enable() and devm_clk_get_prepared() functions
> instead of devm_clk_get_enable() to avoid an extra clock disable
> call from the remove path.
> 
>   Call trace:
>    clk_core_disable+0xb0/0xc0
>    clk_disable+0x30/0x4c
>    clk_disable_unprepare+0x18/0x30
>    devm_clk_release+0x24/0x40
>    devres_release_all+0xc8/0x190
>    device_unbind_cleanup+0x18/0x6c
>    device_release_driver_internal+0x20c/0x250
>    device_release_driver+0x18/0x24
>    bus_remove_device+0x124/0x130
>    device_del+0x174/0x440
> 
> Fixes: 4de0224c6fbe ("watchdog: of_xilinx_wdt: Use devm_clk_get_enabled() helper")
> Signed-off-by: Srinivas Neeli <srinivas.neeli@....com>
> ---
>   drivers/watchdog/of_xilinx_wdt.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/of_xilinx_wdt.c b/drivers/watchdog/of_xilinx_wdt.c
> index 05657dc1d36a..777272f7d326 100644
> --- a/drivers/watchdog/of_xilinx_wdt.c
> +++ b/drivers/watchdog/of_xilinx_wdt.c
> @@ -187,7 +187,7 @@ static int xwdt_probe(struct platform_device *pdev)
>   
>   	watchdog_set_nowayout(xilinx_wdt_wdd, enable_once);
>   
> -	xdev->clk = devm_clk_get_enabled(dev, NULL);
> +	xdev->clk = devm_clk_get_prepared(dev, NULL);
>   	if (IS_ERR(xdev->clk)) {
>   		if (PTR_ERR(xdev->clk) != -ENOENT)
>   			return PTR_ERR(xdev->clk);
> @@ -218,18 +218,24 @@ static int xwdt_probe(struct platform_device *pdev)
>   	spin_lock_init(&xdev->spinlock);
>   	watchdog_set_drvdata(xilinx_wdt_wdd, xdev);
>   
> +	rc = clk_enable(xdev->clk);
> +	if (rc) {
> +		dev_err(dev, "unable to enable clock\n");
> +		return rc;
> +	}
> +
>   	rc = xwdt_selftest(xdev);
>   	if (rc == XWT_TIMER_FAILED) {
>   		dev_err(dev, "SelfTest routine error\n");

Needs clk_disable() here as well.

Guenter

>   		return rc;
>   	}
>   
> +	clk_disable(xdev->clk);
> +
>   	rc = devm_watchdog_register_device(dev, xilinx_wdt_wdd);
>   	if (rc)
>   		return rc;
>   
> -	clk_disable(xdev->clk);
> -
>   	dev_info(dev, "Xilinx Watchdog Timer with timeout %ds\n",
>   		 xilinx_wdt_wdd->timeout);
>