linux-kernel - Re: [PATCH v4] leds: simatic-ipc-leds-gpio: make sure we have the GPIO providing driver

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Date:   Thu, 22 Dec 2022 11:19:15 +0100
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:     Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH v4] leds: simatic-ipc-leds-gpio: make sure we have the
 GPIO providing driver

Ping. This still applies and still is relevant. Maybe got lost or stuck
in the LED subsystem.

Henning

Am Fri, 7 Oct 2022 17:33:23 +0200
schrieb Henning Schild <henning.schild@...mens.com>:

> 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 no 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") Reviewed-by: Andy Shevchenko
> <andy.shevchenko@...il.com> 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
> b9eeb8702df0..fb8d427837db 100644 ---
> a/drivers/leds/simple/simatic-ipc-leds-gpio.c +++
> b/drivers/leds/simple/simatic-ipc-leds-gpio.c @@ -77,6 +77,8 @@
> static int simatic_ipc_leds_gpio_probe(struct platform_device *pdev) 
>  	switch (plat->devmode) {
>  	case SIMATIC_IPC_DEVICE_127E:
> +		if (!IS_ENABLED(CONFIG_PINCTRL_BROXTON))
> +			return -ENODEV;
>  		simatic_ipc_led_gpio_table =
> &simatic_ipc_led_gpio_table_127e; break;
>  	case SIMATIC_IPC_DEVICE_227G: