Re: [PATCH -next] net: dsa: mv88e6xxx: Fix build warning when CONFIG_NET_DSA_LEGACY is n

From: Florian Fainelli <f.fainelli@gmail.com>
To: Heiner Kallweit <hkallweit1@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Zhangshaokun <zhangshaokun@hisilicon.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Vivien Didelot <vivien.didelot@gmail.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH -next] net: dsa: mv88e6xxx: Fix build warning when CONFIG_NET_DSA_LEGACY is n
Date: Mon, 4 Mar 2019 10:24:38 -0800	[thread overview]
Message-ID: <04ec6023-7385-d4ad-0bae-2c23e691c6f5@gmail.com> (raw)
In-Reply-To: <74a6581e-f761-0fb0-3200-e82b7ac88e75@gmail.com>

On 3/4/19 10:18 AM, Heiner Kallweit wrote:
> On 04.03.2019 15:57, Andrew Lunn wrote:
>> On Mon, Mar 04, 2019 at 10:16:08PM +0800, Zhangshaokun wrote:
>>> Hi Andrew,
>>>
>>> On 2019/3/4 21:26, Andrew Lunn wrote:
>>>> On Mon, Mar 04, 2019 at 08:43:01PM +0800, Shaokun Zhang wrote:
>>>>> When CONFIG_NET_DSA_LEGACY is n, there is a GCC bulid warning:
>>>>> drivers/net/dsa/mv88e6xxx/chip.c:4623:13: warning: ‘mv88e6xxx_ports_cmode_init’ defined but not used [-Wunused-function]
>>>>> static void mv88e6xxx_ports_cmode_init(struct mv88e6xxx_chip *chip)
>>>>> Let's fix it.
>>>>
>>>> Hi Shaokun, Heiner
>>>>
>>>> Although this fixes the warning, i suspect there i something wrong
>>>> with the original patch adding mv88e6390x_port_set_cmode(). It should
>>>> also be used without CONFIG_NET_DSA_LEGACY.
>>>
>>> I checked the commit-id 2a93c1a3651f ("net: dsa: Allow compiling out legacy support") by Florian.
>>> Do you mean that CONFIG_NET_DSA_LEGACY shall be removed completely? :-)
>>
>> No, i suspect mv88e6390x_ports_cmode_init() is being called from the
>> wrong place, or needs to be called from a second location.
>>
>> [Goes and looks at the code]
>>
>> Yes, it should also be called in mv88e6xxx_probe(). I would call it
>> just after the call to mv88e6xxx_detect(), so that it is the same as
>> in mv88e6xxx_drv_probe().
>>
>> There are two ways DSA drivers can be probed. The legacy way, which is
>> optional, and is slowly getting removed, and the current way. Heiner
>> is new to DSA and probably missed that, and only handled the legacy
>> probe method. I also missed checking when i reviewed to patch :-(
>>
> Right, I missed that, will submit a fix.
> 
> I just saw that the Kconfig entry comment for NET_DSA_LEGACY says:
> "This feature is scheduled for removal in 4.17."
> 
> Was forgotten to remove it or did somebody scream loud enough
> "But I depend on it" ?

The intent was to remove it by that kernel version but the 88e6060
driver still depends on it, and there appears to be some active users
that Andrew worked with.
-- 
Florian