linux-kernel - Re: [PATCH 1/3] watchdog: s3c2410_wdt: Fold s3c2410_get_wdt_drv

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Message-ID: <20230306174722.rl2fws2p7pseo465@pengutronix.de>
Date:   Mon, 6 Mar 2023 18:47:22 +0100
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        linux-samsung-soc@...r.kernel.org,
        Alim Akhtar <alim.akhtar@...sung.com>,
        linux-kernel@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        kernel@...gutronix.de, Wim Van Sebroeck <wim@...ux-watchdog.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH 1/3] watchdog: s3c2410_wdt: Fold
 s3c2410_get_wdt_drv_data() into only caller

On Mon, Mar 06, 2023 at 09:17:23AM -0800, Guenter Roeck wrote:
> On 3/6/23 01:09, Uwe Kleine-König wrote:
> > s3c2410_get_wdt_drv_data() is only called by s3c2410wdt_probe(), so the
> > implementation of the former can move to the latter.
> > 
> > scripts/bloat-o-meter reports for this change (on an ARCH=arm
> > allmodconfig build):
> > 
> > 	add/remove: 1/1 grow/shrink: 0/2 up/down: 4/-129 (-125)
> > 
> 
> The reason for separating functions in this case wasn't that the separate function
> would be called several times. It was to improve code readability. If anything,
> I would argue that it might sense to split the already lengthy probe function
> further instead of combining it.

Agreed. For dev_err_probe() to work the following would be alternatively
possible:

diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index 58b262ca4e88..564919717761 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
+	wdt->drv_data = variant;
 
-	return 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,

I didn't check if it's the same as for my initial patch #1, but for an
allmodconfig ARCH=arm build this also has a nice bloatometer output:

	add/remove: 1/1 grow/shrink: 0/1 up/down: 4/-104 (-100)

This would allow to make use of dev_err_probe() in
s3c2410_get_wdt_drv_data() and still maintain the split into two
functions.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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