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Date:   Mon, 22 Mar 2021 13:02:04 +0200
From:   Eli Billauer <eli.billauer@gmail.com>
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To:     Greg KH <gregkh@linuxfoundation.org>
CC:     arnd@arndb.de, devel@driverdev.osuosl.org,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        dan.carpenter@oracle.com
Subject: Re: [PATCH v4 1/2] char: xillybus: Move class-related functions to
 new xillybus_class.c
References: <20210311095033.20956-1-eli.billauer@gmail.com> <20210311095033.20956-2-eli.billauer@gmail.com> <YFc65bvAN3/ZNsww@kroah.com>
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On 21/03/21 14:24, Greg KH wrote:
>> +config XILLYBUS_CLASS
>> >  +	tristate
>> >  +
>> >    config XILLYBUS
>> >    	tristate "Xillybus generic FPGA interface"
>> >    	depends on PCI || OF
>> >    	select CRC32
>> >  +	select XILLYBUS_CLASS
>>      
> depends on, do not select.
>
>    
XILLYBUS and XILLYBUS_PCIE are currently enabled as M in several Linux 
distributions. Making them depend on, rather than select XILLYBUS_CLASS 
is likely to disable the driver in those distributions.

With "select", "make oldconfig" sets XILLYBUS_CLASS to the correct value 
smoothly and silently.

Besides, isn't this the intended use case for "select"? A config symbol 
that doesn't depend on anything else, and solves a technical need to 
compile Y if X is enabled?

Or is there a way to use "depends on" without this problem?

Regards,
    Eli