linux-kernel - [PATCH v2] leds: simatic-ipc-leds-gpio: make sure we have the GPIO providing driver

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Message-ID: <20220824131428.31904-1-henning.schild@siemens.com>
Date:   Wed, 24 Aug 2022 15:14:28 +0200
From:   Henning Schild <henning.schild@...mens.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>,
        <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Henning Schild <henning.schild@...mens.com>
Subject: [PATCH v2] leds: simatic-ipc-leds-gpio: make sure we have the GPIO providing driver

If we register a "leds-gpio" platform device for GPIO pins that do not
exist we get a -EPROBE_DEFER and the probe will be tried again later.
If there is not driver to provide that pin we will poll forever and also
create a lot of log messages.

So check if that GPIO driver is configured, if so it will come up
eventually. If not we exit our probe function early and do not even
bother registering the "leds-gpio". This method was chosen over "Kconfig
depends" since this way we can add support for more devices and GPIO
backends more easily without "depends"ing on all GPIO backends.

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 | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/leds/simple/simatic-ipc-leds-gpio.c b/drivers/leds/simple/simatic-ipc-leds-gpio.c
index 4c9e663a90ba..0c96ba98e338 100644
--- a/drivers/leds/simple/simatic-ipc-leds-gpio.c
+++ b/drivers/leds/simple/simatic-ipc-leds-gpio.c
@@ -57,6 +57,8 @@ static int simatic_ipc_leds_gpio_probe(struct platform_device *pdev)
 	struct gpio_desc *gpiod;
 	int err;

+	if (!IS_ENABLED(CONFIG_PINCTRL_BROXTON))
+		return -ENODEV;
 	gpiod_add_lookup_table(&simatic_ipc_led_gpio_table);
 	simatic_leds_pdev = platform_device_register_resndata(NULL,
 		"leds-gpio", PLATFORM_DEVID_NONE, NULL, 0,
-- 
2.35.1