linux-kernel - [PATCH] leds: simatic-ipc-leds-gpio: do not run into endless EPROBE

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Date:   Wed, 25 Jan 2023 19:17:11 +0100
From:   Henning Schild <henning.schild@...mens.com>
To:     Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Henning Schild <henning.schild@...mens.com>
Subject: [PATCH] leds: simatic-ipc-leds-gpio: do not run into endless EPROBE_DEFER loop

Should the driver providing our GPIOs not be available we used to return
-EPORBE_DEFER out of the probe function and cause a potentially endless
loop that also printed a lot to the kernel log.

...
leds-gpio leds-gpio: cannot find GPIO chip igpio-f7188x-2, deferring
leds-gpio leds-gpio: Skipping unavailable LED gpio 0 (red:status-1)
...

The "leds-gpio" just ignores all entries and would never try again even
if the GPIOs show up later. But our extra two GPIOs could cause that
loop, in which we would even register/unregister "leds-gpio" and cause
all the printing.

If any of those two extra GPIOs is not there, return with -ENODEV
instead of -EPROBE_DEFER.

Fixes: a6c80bec3c93 ("leds: simatic-ipc-leds-gpio: Add GPIO version of Siemens driver")
Signed-off-by: Henning Schild <henning.schild@...mens.com>
---
 drivers/leds/simple/simatic-ipc-leds-gpio.c | 29 +++++++++------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/drivers/leds/simple/simatic-ipc-leds-gpio.c b/drivers/leds/simple/simatic-ipc-leds-gpio.c
index 07f0d79d604d..4e2595e684c6 100644
--- a/drivers/leds/simple/simatic-ipc-leds-gpio.c
+++ b/drivers/leds/simple/simatic-ipc-leds-gpio.c
@@ -74,14 +74,13 @@ static int simatic_ipc_leds_gpio_probe(struct platform_device *pdev)
 	const struct simatic_ipc_platform *plat = pdev->dev.platform_data;
 	struct gpio_desc *gpiod;
 	int err;
+	int i;
 
 	switch (plat->devmode) {
 	case SIMATIC_IPC_DEVICE_127E:
 		simatic_ipc_led_gpio_table = &simatic_ipc_led_gpio_table_127e;
 		break;
 	case SIMATIC_IPC_DEVICE_227G:
-		if (!IS_ENABLED(CONFIG_GPIO_F7188X))
-			return -ENODEV;
 		request_module("gpio-f7188x");
 		simatic_ipc_led_gpio_table = &simatic_ipc_led_gpio_table_227g;
 		break;
@@ -99,21 +98,19 @@ static int simatic_ipc_leds_gpio_probe(struct platform_device *pdev)
 		goto out;
 	}
 
-	/* PM_BIOS_BOOT_N */
-	gpiod = gpiod_get_index(&simatic_leds_pdev->dev, NULL, 6, GPIOD_OUT_LOW);
-	if (IS_ERR(gpiod)) {
-		err = PTR_ERR(gpiod);
-		goto out;
-	}
-	gpiod_put(gpiod);
-
-	/* PM_WDT_OUT */
-	gpiod = gpiod_get_index(&simatic_leds_pdev->dev, NULL, 7, GPIOD_OUT_LOW);
-	if (IS_ERR(gpiod)) {
-		err = PTR_ERR(gpiod);
-		goto out;
+	for (i = 0; i < 2; i++) {
+		gpiod = gpiod_get_index(&simatic_leds_pdev->dev, NULL,
+					ARRAY_SIZE(simatic_ipc_gpio_leds) + i, GPIOD_OUT_LOW);
+		if (IS_ERR(gpiod)) {
+			err = PTR_ERR(gpiod);
+			if (err == -EPROBE_DEFER) {
+				dev_err(&pdev->dev, "GPIO driver seems missing\n");
+				err = -ENODEV;
+			}
+			goto out;
+		}
+		gpiod_put(gpiod);
 	}
-	gpiod_put(gpiod);
 
 	return 0;
 out:
-- 
2.39.1