linux-kernel - Re: [PATCH] drivers/video: fix mb862xx

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Message-ID: <532CC707.9010405@infradead.org>
Date:	Fri, 21 Mar 2014 16:11:03 -0700
From:	Randy Dunlap <rdunlap@...radead.org>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>
CC:	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jim Davis <jim.epost@...il.com>,
	Fengguang Wu <fengguang.wu@...el.com>
Subject: Re: [PATCH] drivers/video: fix mb862xx_i2c depends issue build failure

On 03/21/2014 06:53 AM, Paul Gortmaker wrote:
> On 14-03-21 09:32 AM, Tomi Valkeinen wrote:
>> Hi,
>>
>> On 20/03/14 17:16, Paul Gortmaker wrote:
>>> Any randconfig that sets I2C=m and FB_MB862XX_I2C=y will
>>> encounter a final link failure that looks like this:
>>
>> It compiles fine with I2C=m, FB_MB862XX=m and FB_MB862XX_I2C=y.
>>
>>> drivers/built-in.o: In function `mb862xx_i2c_init':
>>> drivers/video/mb862xx/mb862xx-i2c.c:165: undefined reference to `i2c_add_adapter'
>>> drivers/built-in.o: In function `mb862xx_i2c_exit':
>>> drivers/video/mb862xx/mb862xx-i2c.c:176: undefined reference to `i2c_del_adapter'
>>>
>>> Since FB_MB862XX_I2C is a bool and not tristate, simply
>>> don't offer it at all if core I2C support is not built in.
>>
>> FB_MB862XX_I2C is not a driver, it just adds the i2c support to
>> FB_MB862XX. The relevant thing is whether FB_MB862XX is m or y, so
>> compiling with:
>>
>> I2C=m, FB_MB862XX=y and FB_MB862XX_I2C=y
>>
>> will fail.
> 
> How would you suggest we fix it then?  Perhaps we could simplify the
> Kconfig space and just get rid of FB_MB862XX_I2C entirely?  Is there
> ever a reason why someone would want it turned off when I2C is present?
> 
> Paul.
> --
> 
>>
>>> Reported-by: Jim Davis <jim.epost@...il.com>
>>> Reported-by: Fengguang Wu <fengguang.wu@...el.com>
>>> Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
>>>
>>> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
>>> index dade5b7699bc..aefd1b9a3cbd 100644
>>> --- a/drivers/video/Kconfig
>>> +++ b/drivers/video/Kconfig
>>> @@ -2338,7 +2338,7 @@ endchoice
>>>  
>>>  config FB_MB862XX_I2C
>>>  	bool "Support I2C bus on MB862XX GDC"
>>> -	depends on FB_MB862XX && I2C
>>> +	depends on FB_MB862XX && I2C=y
>>>  	default y
>>>  	help
>>>  	  Selecting this option adds Coral-P(A)/Lime GDC I2C bus adapter
>>
>> This fix is not correct, as it prevents the following, valid, config:
>>
>> I2C=m, FB_MB862XX=m and FB_MB862XX_I2C=y

If I am following this correctly, this kconfig situation is often handled
by something like

	depends on I2C=y || I2C=FB_MB862XX



-- 
~Randy
--
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