linux-kernel - Re: [PATCH TRIVIAL 1/5] Input: keyboard: use macro module_platform

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Message-ID: <CAMuHMdU1fv-Qx1dRstFjBkqcKswWCu34Hkeusk1vW3ReXB7CDA@mail.gmail.com>
Date:	Tue, 10 Jan 2012 21:57:08 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	JJ Ding <jj_ding@....com.tw>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Grant Likely <grant.likely@...retlab.ca>,
	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
	JJ Ding <dgdunix@...il.com>
Subject: Re: [PATCH TRIVIAL 1/5] Input: keyboard: use macro module_platform_driver()

On Tue, Jan 10, 2012 at 21:47, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> On Tue, Nov 22, 2011 at 10:00, JJ Ding <jj_ding@....com.tw> wrote:
>> From: JJ Ding <dgdunix@...il.com>
>>
>> Commit 940ab88962bc1aff3273a8356d64577a6e386736 introduced a new macro to
>> save some platform_driver boilerplate code. Use it.
>
>> diff --git a/drivers/input/keyboard/amikbd.c b/drivers/input/keyboard/amikbd.c
>> index 79172af..6df5f6a 100644
>> --- a/drivers/input/keyboard/amikbd.c
>> +++ b/drivers/input/keyboard/amikbd.c
>> @@ -259,19 +259,6 @@ static struct platform_driver amikbd_driver = {
>>                .owner  = THIS_MODULE,
>>        },
>>  };
>> -
>> -static int __init amikbd_init(void)
>> -{
>> -       return platform_driver_probe(&amikbd_driver, amikbd_probe);
>> -}
>> -
>> -module_init(amikbd_init);
>> -
>> -static void __exit amikbd_exit(void)
>> -{
>> -       platform_driver_unregister(&amikbd_driver);
>> -}
>> -
>> -module_exit(amikbd_exit);
>> +module_platform_driver(amikbd_driver);
>>
>>  MODULE_ALIAS("platform:amiga-keyboard");
>
> Sorry for not noticing before, but this is not correct.
> Drivers using platform_driver_probe() typically don't fill in the
> platform_driver.probe
> method, as it's passed explicitly to platform_driver_probe() instead.
> Hence amikbd_probe() is now referenced nowhere, and thus never called
> (doesn't the compiler warn about amikbd_probe() being defined but unused?).
>
>> diff --git a/drivers/input/keyboard/davinci_keyscan.c b/drivers/input/keyboard/davinci_keyscan.c
>> index 9d82b3a..4698252 100644
>> --- a/drivers/input/keyboard/davinci_keyscan.c
>> +++ b/drivers/input/keyboard/davinci_keyscan.c
>> @@ -328,18 +328,7 @@ static struct platform_driver davinci_ks_driver = {
>>        },
>>        .remove = __devexit_p(davinci_ks_remove),
>>  };
>> -
>> -static int __init davinci_ks_init(void)
>> -{
>> -       return platform_driver_probe(&davinci_ks_driver, davinci_ks_probe);
>> -}
>> -module_init(davinci_ks_init);
>> -
>> -static void __exit davinci_ks_exit(void)
>> -{
>> -       platform_driver_unregister(&davinci_ks_driver);
>> -}
>> -module_exit(davinci_ks_exit);
>> +module_platform_driver(davinci_ks_driver);
>>
>>  MODULE_AUTHOR("Miguel Aguilar");
>>  MODULE_DESCRIPTION("Texas Instruments DaVinci Key Scan Driver");
>
> Same here, I think.

And looking for platform_driver_probe() in recent changesets, I found
a few more:

drivers/input/touchscreen/atmel-wm97xx.c atmel_wm97xx_probe
drivers/input/touchscreen/mc13783_ts.c mc13783_ts_probe
drivers/input/serio/at32psif.c psif_probe
drivers/input/mouse/amimouse.c amimouse_probe

Interestingly, in drivers/input/misc/twl4030-pwrbutton.c you did make
platform_driver.probe point to twl4030_pwrbutton_probe().
But that one is also broken, as twl4030_pwrbutton_probe() is marked __init,
which is no longer correct.

Still, setting up platform_driver.probe and removing __init from all probe
functions is not the right thing to do, as this make (non-__init) kernel code
size bigger, while none of these devices are hotpluggable and thus cannot
appear after bootup. That's why we have platform_driver_probe() in the
first place. So I think all of this should be reverted for non-hotpluggable
drivers.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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