Messages in this thread Patch in this message | | | Date | Fri, 5 Aug 2022 14:19:20 +0200 | From | Henning Schild <> | Subject | Re: [PATCH] leds: simatic-ipc-leds-gpio: make sure we have the GPIO providing driver |
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This applies on top of "[PATCH v6 00/12] platform/x86: introduce p2sb_bar() helper"
where it could also be squashed into p12.
Am Fri, 5 Aug 2022 14:03:43 +0200 schrieb Henning Schild <henning.schild@siemens.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 not driver to provide that pin we will poll forever and > also create a lot of log messages.
When i did build a kernel without PINCTRL_BROXTON and booted that, i quickly filled up my disk with gigabytes of log messages from "leds-gpio".
> 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.
The series "[PATCH 0/4] add support for another simatic board" shows how a second board would be added, using
if (!IS_ENABLED(CONFIG_GPIO_F7188X)) return -ENODEV;
I am not too happy with the solution. But it is better than "depends" because we do not need to build all possible GPIO providers if we want a minimal kernel for a board, while having all simatic gpio based boards in one led driver.
And we will anyhow need to "name the provider" in case it does not auto-probe. Also to be seen in that other series where we
request_module("gpio-f7188x");
regards, Henning
> Signed-off-by: Henning Schild <henning.schild@siemens.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,
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