linux-kernel - Re: [PATCH v2 1/2] watchdog: s3c2410: Make s3c2410_get_wdt_drv

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Message-ID: <84ba9412-d7f7-4102-93b0-372d4a5a06a0@roeck-us.net>
Date:   Tue, 7 Mar 2023 08:37:08 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel@...gutronix.de
Subject: Re: [PATCH v2 1/2] watchdog: s3c2410: Make
 s3c2410_get_wdt_drv_data() return an int

On Tue, Mar 07, 2023 at 07:56:02AM +0100, Uwe Kleine-König wrote:
> This is a preparation for making more use of dev_err_probe(). The idea
> is that s3c2410_get_wdt_drv_data() (as it's called only by .probe()) can
> make effective use of dev_err_probe() only if it returns an int. For
> that the assignment to wdt->drv_data has to happen in the function. The
> caller can then just pass on the return value in the error case.
> 
> This seems to be nicer for the compiler: bloatometer reports for an
> ARCH=arm s3c6400_defconfig build:
> 
> 	add/remove: 1/1 grow/shrink: 0/1 up/down: 4/-64 (-60)
> 	Function                                     old     new   delta
> 	__initcall__kmod_s3c2410_wdt__209_821_s3c2410wdt_driver_init6       -       4      +4
> 	__initcall__kmod_s3c2410_wdt__209_819_s3c2410wdt_driver_init6       4       -      -4
> 	s3c2410wdt_probe                            1332    1272     -60
> 
> There is no semantical change. (Just one minor difference: Before this
> patch wdt->drv_data was always assigned, now that only happens in the
> non-error case. That doesn't matter however as *wdt is freed in the
> error case.)
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/watchdog/s3c2410_wdt.c | 22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 58b262ca4e88..f3de8ef499c3 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -579,8 +579,8 @@ static inline unsigned int s3c2410wdt_get_bootstatus(struct s3c2410_wdt *wdt)
>  	return 0;
>  }
>  
> -static inline const struct s3c2410_wdt_variant *
> -s3c2410_get_wdt_drv_data(struct platform_device *pdev)
> +static inline int
> +s3c2410_get_wdt_drv_data(struct platform_device *pdev, struct s3c2410_wdt *wdt)
>  {
>  	const struct s3c2410_wdt_variant *variant;
>  	struct device *dev = &pdev->dev;
> @@ -603,24 +603,26 @@ s3c2410_get_wdt_drv_data(struct platform_device *pdev)
>  					   "samsung,cluster-index", &index);
>  		if (err) {
>  			dev_err(dev, "failed to get cluster index\n");
> -			return NULL;
> +			return -EINVAL;
>  		}
>  
>  		switch (index) {
>  		case 0:
> -			return variant;
> +			break;
>  		case 1:
> -			return (variant == &drv_data_exynos850_cl0) ?
> +			variant = (variant == &drv_data_exynos850_cl0) ?
>  				&drv_data_exynos850_cl1 :
>  				&drv_data_exynosautov9_cl1;
> +			break;
>  		default:
>  			dev_err(dev, "wrong cluster index: %u\n", index);
> -			return NULL;
> +			return -EINVAL;
>  		}
>  	}
>  #endif
>  
> -	return variant;
> +	wdt->drv_data = variant;
> +	return 0;
>  }
>  
>  static void s3c2410wdt_wdt_disable_action(void *data)
> @@ -644,9 +646,9 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>  	spin_lock_init(&wdt->lock);
>  	wdt->wdt_device = s3c2410_wdd;
>  
> -	wdt->drv_data = s3c2410_get_wdt_drv_data(pdev);
> -	if (!wdt->drv_data)
> -		return -EINVAL;
> +	ret = s3c2410_get_wdt_drv_data(pdev, wdt);
> +	if (ret)
> +		return ret;
>  
>  	if (wdt->drv_data->quirks & QUIRKS_HAVE_PMUREG) {
>  		wdt->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
> -- 
> 2.39.1
>