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Subject: Re: [PATCH v2 0/7] Add PTP support for BCM53128 switch
To:     Martin Kaistra <martin.kaistra@linutronix.de>,
        Vladimir Oltean <olteanv@gmail.com>
Cc:     Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Richard Cochran <richardcochran@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        John Stultz <john.stultz@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Stephen Boyd <sboyd@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org
References: <20211109095013.27829-1-martin.kaistra@linutronix.de>
 <20211109103936.2wjvvwhihhfqjfot@skbuf>
 <eb5836a7-fe08-7764-596b-f3941128f89c@linutronix.de>
From:   Florian Fainelli <f.fainelli@gmail.com>
Message-ID: <f88555e0-88b7-d01c-92ed-33729f704c4c@gmail.com>
Date:   Tue, 9 Nov 2021 10:13:18 -0800
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On 11/9/21 3:13 AM, Martin Kaistra wrote:
> 
> 
> Am 09.11.21 um 11:39 schrieb Vladimir Oltean:
>> On Tue, Nov 09, 2021 at 10:50:02AM +0100, Martin Kaistra wrote:
>>> Ideally, for the B53=m case, I would have liked to include the PTP
>>> support in the b53_module itself, however I couldn't find a way to do
>>> that without renaming either the common source file or the module, which
>>> I didn't want to do.
>>>
>>> Instead, b53_ptp will be allowed as a loadable module, but only if
>>> b53_common is also a module, otherwise it will be built-in.
>>
>> Does this not work?
>>
>> obj-$(CONFIG_B53)        += b53_common.o
>>
>> ifdef CONFIG_B53_PTP
>> b53_common-objs += b53_ptp.o
>> endif
>>
>> (haven't tried though)
>>
> 
> I get:
> 
> arm-linux-gnueabihf-ld  -EL    -r -o drivers/net/dsa/b53/b53_common.o
> drivers/net/dsa/b53/b53_ptp.o
> 
> 
> 
> and
> 
> 
> 
> ERROR: modpost: "b53_switch_register" [drivers/net/dsa/b53/b53_mdio.ko]
> undefined!
> 
> ERROR: modpost: "b53_switch_alloc" [drivers/net/dsa/b53/b53_mdio.ko]
> undefined!
> 
> ERROR: modpost: "b53_switch_register" [drivers/net/dsa/b53/b53_spi.ko]
> undefined!
> 
> ERROR: modpost: "b53_switch_alloc" [drivers/net/dsa/b53/b53_spi.ko]
> undefined!
> 
> It seems to me, that b53_common.c does not get included at all.

You need to play tricks with '-' and '_' and do something like this:

obj-$(CONFIG_B53)	+= b53-common.o

b53-common-objs		+= b53_common.o b53_ptp.o

and that should result in a b53-common.ko which would be accepted by
modprobe b53_common or b53-common AFAICT.
-- 
Florian