Am Wed, 25 Jan 2023 19:17:11 +0100
schrieb Henning Schild <henning.schild@xxxxxxxxxxx>:
> 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.
This is a really bad idea. The real fix for the future will be to
write individual drivers which clearly describe their dep chains.
This patch should not be merged.
Henning
> Fixes: a6c80bec3c93 ("leds: simatic-ipc-leds-gpio: Add GPIO version
> of Siemens driver") Signed-off-by: Henning Schild
> <henning.schild@xxxxxxxxxxx> ---
> 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:
