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Subject: Re: [PATCH] net: phy: add driver for Motorcomm yt8511 phy
To:     Leon Romanovsky <leon@kernel.org>, Peter Geis <pgwipeout@gmail.com>
Cc:     Andrew Lunn <andrew@lunn.ch>, Russell King <linux@armlinux.org.uk>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>
References: <20210511214605.2937099-1-pgwipeout@gmail.com>
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 <CAMdYzYrV0T9H1soxSVpQv=jLCR9k9tuJddo1Kw-c3O5GJvg92A@mail.gmail.com>
 <YKTJwscaV1WaK98z@unreal>
From:   Heiner Kallweit <hkallweit1@gmail.com>
Message-ID: <cbfecaf2-2991-c79e-ba80-c805d119ac2f@gmail.com>
Date:   Wed, 19 May 2021 12:37:43 +0200
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On 19.05.2021 10:18, Leon Romanovsky wrote:
> On Tue, May 18, 2021 at 08:20:03PM -0400, Peter Geis wrote:
>> On Tue, May 18, 2021 at 4:59 AM Leon Romanovsky <leon@kernel.org> wrote:
>>>
>>> On Tue, May 11, 2021 at 05:46:06PM -0400, Peter Geis wrote:
>>>> Add a driver for the Motorcomm yt8511 phy that will be used in the
>>>> production Pine64 rk3566-quartz64 development board.
>>>> It supports gigabit transfer speeds, rgmii, and 125mhz clk output.
>>>>
>>>> Signed-off-by: Peter Geis <pgwipeout@gmail.com>
>>>> ---
>>>>  MAINTAINERS                 |  6 +++
>>>>  drivers/net/phy/Kconfig     |  6 +++
>>>>  drivers/net/phy/Makefile    |  1 +
>>>>  drivers/net/phy/motorcomm.c | 85 +++++++++++++++++++++++++++++++++++++
>>>>  4 files changed, 98 insertions(+)
>>>>  create mode 100644 drivers/net/phy/motorcomm.c
>>>
>>> <...>
>>>
>>>> +static const struct mdio_device_id __maybe_unused motorcomm_tbl[] = {
>>>> +     { PHY_ID_MATCH_EXACT(PHY_ID_YT8511) },
>>>> +     { /* sentinal */ }
>>>> +}
>>>
>>> Why is this "__maybe_unused"? This *.c file doesn't have any compilation option
>>> to compile part of it.
>>>
>>> The "__maybe_unused" is not needed in this case.
>>
>> I was simply following convention, for example the realtek.c,
>> micrel.c, and smsc.c drivers all have this as well.
> 
> Maybe they have a reason, but this specific driver doesn't have such.
> 

It's used like this:
MODULE_DEVICE_TABLE(mdio, <mdio_device_id_tbl>);

And MODULE_DEVICE_TABLE is a no-op if MODULE isn't defined:

#ifdef MODULE
/* Creates an alias so file2alias.c can find device table. */
#define MODULE_DEVICE_TABLE(type, name)					\
extern typeof(name) __mod_##type##__##name##_device_table		\
  __attribute__ ((unused, alias(__stringify(name))))
#else  /* !MODULE */
#define MODULE_DEVICE_TABLE(type, name)
#endif

In this case the table is unused.

> Thanks
> 
>>
>>>
>>> Thanks