linux-kernel - Re: [PATCH 2/3] leds: simatic-ipc-leds-gpio: split up into multiple drivers

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Message-ID: <bf678bc5-9615-31a3-3039-5d013f9c9f25@redhat.com>
Date:   Wed, 1 Mar 2023 15:53:04 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Henning Schild <henning.schild@...mens.com>
Cc:     Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>,
        Mark Gross <markgross@...nel.org>,
        linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org,
        platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH 2/3] leds: simatic-ipc-leds-gpio: split up into multiple
 drivers

Hi,

On 2/21/23 15:51, Andy Shevchenko wrote:
> On Tue, Feb 21, 2023 at 03:43:54PM +0100, Henning Schild wrote:
>> Am Tue, 21 Feb 2023 15:51:03 +0200
>> schrieb Andy Shevchenko <andriy.shevchenko@...ux.intel.com>:
>>> On Tue, Feb 21, 2023 at 01:24:13PM +0100, Henning Schild wrote:
>>>> In order to clearly describe the dependencies between the gpio  
> 
> ...
> 
>>>> +#ifndef __DRIVERS_LEDS_SIMPLE_SIMATIC_IPC_LEDS_GPIO
>>>> +#define __DRIVERS_LEDS_SIMPLE_SIMATIC_IPC_LEDS_GPIO  
>>>
>>>> +#endif /* __DRIVERS_LEDS_SIMPLE_SIMATIC_IPC_LEDS_GPIO */  
>>>
>>> This header doesn't look right.
>>>
>>> Have you run `make W=1 ...` against your patches?
>>
>> No reports.
>>
>>> Even if it doesn't show defined but unused errors
>>> the idea is that this should be a C-file, called,
>>> let's say, ...-core.c.
>>
>> When i started i kind of had a -common.c in mind as well. But then the
>> header idea came and i gave it a try, expecting questions in the review.
>>
>> It might be a bit unconventional but it seems to do the trick pretty
>> well. Do you see a concrete problem or a violation of a rule?
> 
> Exactly as described above. The header approach means that *all* static
> definitions must be used by each user of that file. Otherwise you will
> get "defined but not used" compiler warning.
> 
> And approach itself is considered (at least by me) as a hackish way to
> achieve what usually should be done via C-file.
> 
> So, if maintainers are okay, I wouldn't have objections, but again
> I do not think it's a correct approach.

I agree with Andy here, please add a -common.o file with a shared
probe() helper which gets the 2 different gpiod_lookup_table-s
as parameter and then put the actual probe() function calling
the helper inside the 2 different .c files.

And all the:

+static struct platform_driver simatic_ipc_led_gpio_driver = {
+	.probe = simatic_ipc_leds_gpio_probe,
+	.remove = simatic_ipc_leds_gpio_remove,
+	.driver = {
+		.name = KBUILD_MODNAME,
+	},
+};
+
+module_platform_driver(simatic_ipc_led_gpio_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" KBUILD_MODNAME);

bits should then also go into the 2 different .c file files.

Really putting something like module_platform_driver() or
MODULE_LICENSE() / MODULE_ALIAS() inside a .h file is
just wrong IMHO.

Regards,

Hans