Re: [PATCH] drivers: Let several drivers depends on HAS_IOMEM for 'devm_ioremap_resource'

From: Chen Gang <gang.chen.5i5j@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>, Richard Weinberger <richard@nod.at>
Cc: Lars-Peter Clausen <lars@metafoo.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	dmitry.torokhov@gmail.com, linux-iio@vger.kernel.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	teg@jklm.no, Thierry Reding <thierry.reding@gmail.com>,
	Lennox Wu <lennox.wu@gmail.com>, Marek Vasut <marex@denx.de>,
	Liqin Chen <liqin.linux@gmail.com>,
	msalter@redhat.com, linux-pwm@vger.kernel.org,
	devel@driverdev.osuosl.org, linux-watchdog@vger.kernel.org,
	linux-input@vger.kernel.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	knaack.h@gmx.de, Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Mischa.Jonker@synopsys.com, jic23@kernel.org, arnd@arndb.de,
	Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [PATCH] drivers: Let several drivers depends on HAS_IOMEM for 'devm_ioremap_resource'
Date: Tue, 15 Jul 2014 22:38:25 +0800	[thread overview]
Message-ID: <53C53CE1.4090803@gmail.com> (raw)
In-Reply-To: <53C47FB7.6080304@gmail.com>

On 07/15/2014 09:11 AM, Chen Gang wrote:
> 
> 
> On 07/15/2014 08:53 AM, Guenter Roeck wrote:
>> On 07/14/2014 05:34 PM, Chen Gang wrote:
>>> On 07/14/2014 05:22 PM, Chen Gang wrote:
>>>>
>>>> 在 2014年7月14日，下午4:57，Richard Weinberger <richard@nod.at> 写道：
>>>>
>>>>> Am 14.07.2014 10:48, schrieb Lars-Peter Clausen:
>>>>>> On 07/14/2014 10:31 AM, Richard Weinberger wrote:
>>>>>>> Am 13.07.2014 22:17, schrieb Greg Kroah-Hartman:
>>>>>>>> On Sun, Jul 13, 2014 at 09:33:38PM +0200, Richard Weinberger wrote:
>>>>>>>>> Maybe we could add COMPILE_TEST to the version string too?
>>>>>>>>> Just to detect such kernels fast in user bug reports...
>>>>>>>>
>>>>>>>> What kind of bug report are you going to get?
>>>>>>>
>>>>>>> User manages to enable CONFIG_FOO by selecting COMPILE_TEST and
>>>>>>> complains that it does not work. :)
>>>>>>
>>>>>> These drivers are typically drivers for some SoC peripheral and the
>>>>>> device will simply physically not exist on a platform that does not
>>>>>> provide HAS_IOMEM. This is not really any
>>>>>> different from making the driver selectable via COMPILE_TEST for
>>>>>> any other platform. To hit the issue you'd have to instantiate a
>>>>>> device driver instance for a device that
>>>>>> physically does not exist. This will always result in a failure.
>>>>>
>>>>> Okay, you have convinced me. :)
>>>>>
>>>
>>> After search the history patches, I found one related patch which made
>>> by myself (when I am in Asianux):
>>>
>>>    "https://lkml.org/lkml/2013/7/1/641"
>>>
>>> For me, it is a long discussion, and forced many members have to join
>>> in. Please help check again.
>>>
>>
>> One thing you could try would be to return NULL (or where appropriate
>> an error) in the #else case of CONFIG_HAS_IOMEM and CONFIG_HAS_IOPORT,
>> ie dont take COMPILE_TEST into account at all. Obviously that means
>> you won't be able to dump a warning message in the COMPILE_TEST
>> case, but at least the code would compile. The rejection of above patch
>> would make a good case for this approach.
>>
> 
> OK, thanks: at least, it can be improved.  But still welcome any other
> opinions of another related members.
> 

If no reply within 3 days (2014-07-18), I shall try to send related
patch for it within this week end (2014-07-20).

Thanks.
-- 
Chen Gang

Open share and attitude like air water and life which God blessed