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Date:   Fri, 31 Mar 2023 17:11:56 +0300
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Subject: Re: [PATCH net-next 14/15] net: dsa: mt7530: introduce driver for
 MT7988 built-in switch
To:     Daniel Golle <daniel@makrotopia.org>
Cc:     netdev@vger.kernel.org, linux-mediatek@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk,
        linux-kernel@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Sean Wang <sean.wang@mediatek.com>,
        Landen Chao <Landen.Chao@mediatek.com>,
        DENG Qingfang <dqfext@gmail.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Sam Shih <Sam.Shih@mediatek.com>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        John Crispin <john@phrozen.org>, Felix Fietkau <nbd@nbd.name>,
        Luiz Angelo Daros de Luca <luizluca@gmail.com>
References: <cover.1680180959.git.daniel@makrotopia.org>
 <fef2cb2fe3d2b70fa46e93107a0c862f53bb3bfa.1680180959.git.daniel@makrotopia.org>
 <6a7c5f81-a8a3-27b5-4af3-7175a3313f9a@arinc9.com>
 <ZCazDBJvFvjcQfKo@makrotopia.org>
 <7d0acaef-0cec-91b9-a5c6-d094b71e3dbd@arinc9.com>
 <28d048c9-6389-749b-d0eb-18a9c2d83c4e@arinc9.com>
 <ZCbpvVqAEHpoAazr@makrotopia.org>
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On 31.03.2023 17:10, Daniel Golle wrote:
> On Fri, Mar 31, 2023 at 04:18:19PM +0300, Arınç ÜNAL wrote:
>> On 31.03.2023 15:06, Arınç ÜNAL wrote:
>>> On 31.03.2023 13:16, Daniel Golle wrote:
>>>> On Fri, Mar 31, 2023 at 08:50:28AM +0300, Arınç ÜNAL wrote:
>>>>> On 30.03.2023 18:23, Daniel Golle wrote:
>>>>>> Add driver for the built-in Gigabit Ethernet switch which can be found
>>>>>> in the MediaTek MT7988 SoC.
>>>>>>
>>>>>> The switch shares most of its design with MT7530 and MT7531, but has
>>>>>> it's registers mapped into the SoCs register space rather than being
>>>>>> connected externally or internally via MDIO.
>>>>>>
>>>>>> Introduce a new platform driver to support that.
>>>>>>
>>>>>> Signed-off-by: Daniel Golle <daniel@makrotopia.org>
>>>>>> ---
>>>>>>     MAINTAINERS                   |   2 +
>>>>>>     drivers/net/dsa/Kconfig       |  12 ++++
>>>>>>     drivers/net/dsa/Makefile      |   1 +
>>>>>>     drivers/net/dsa/mt7530-mmio.c | 101
>>>>>> ++++++++++++++++++++++++++++++++++
>>>>>>     drivers/net/dsa/mt7530.c      |  86 ++++++++++++++++++++++++++++-
>>>>>>     drivers/net/dsa/mt7530.h      |  12 ++--
>>>>>>     6 files changed, 206 insertions(+), 8 deletions(-)
>>>>>>     create mode 100644 drivers/net/dsa/mt7530-mmio.c
>>>>>>
>>>>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>>>>> index 14924aed15ca7..674673dbdfd8b 100644
>>>>>> --- a/MAINTAINERS
>>>>>> +++ b/MAINTAINERS
>>>>>> @@ -13174,9 +13174,11 @@ MEDIATEK SWITCH DRIVER
>>>>>>     M:    Sean Wang <sean.wang@mediatek.com>
>>>>>>     M:    Landen Chao <Landen.Chao@mediatek.com>
>>>>>>     M:    DENG Qingfang <dqfext@gmail.com>
>>>>>> +M:    Daniel Golle <daniel@makrotopia.org>
>>>>>>     L:    netdev@vger.kernel.org
>>>>>>     S:    Maintained
>>>>>>     F:    drivers/net/dsa/mt7530-mdio.c
>>>>>> +F:    drivers/net/dsa/mt7530-mmio.c
>>>>>>     F:    drivers/net/dsa/mt7530.*
>>>>>>     F:    net/dsa/tag_mtk.c
>>>>>> diff --git a/drivers/net/dsa/Kconfig b/drivers/net/dsa/Kconfig
>>>>>> index c2551b13324c2..de4d86e37973f 100644
>>>>>> --- a/drivers/net/dsa/Kconfig
>>>>>> +++ b/drivers/net/dsa/Kconfig
>>>>>> @@ -52,6 +52,18 @@ config NET_DSA_MT7530
>>>>>>           Multi-chip module MT7530 in MT7621AT, MT7621DAT, MT7621ST and
>>>>>>           MT7623AI SoCs is supported as well.
>>>>>> +config NET_DSA_MT7988
>>>>>> +    tristate "MediaTek MT7988 built-in Ethernet switch support"
>>>>>> +    select NET_DSA_MT7530_COMMON
>>>>>> +    depends on HAS_IOMEM
>>>>>> +    help
>>>>>> +      This enables support for the built-in Ethernet switch found
>>>>>> +      in the MediaTek MT7988 SoC.
>>>>>> +      The switch is a similar design as MT7531, however, unlike
>>>>>> +      other MT7530 and MT7531 the switch registers are directly
>>>>>> +      mapped into the SoCs register space rather than being accessible
>>>>>> +      via MDIO.
>>>>>> +
>>>>>>     config NET_DSA_MV88E6060
>>>>>>         tristate "Marvell 88E6060 ethernet switch chip support"
>>>>>>         select NET_DSA_TAG_TRAILER
>>>>>> diff --git a/drivers/net/dsa/Makefile b/drivers/net/dsa/Makefile
>>>>>> index 71250d7dd41af..103a33e20de4b 100644
>>>>>> --- a/drivers/net/dsa/Makefile
>>>>>> +++ b/drivers/net/dsa/Makefile
>>>>>> @@ -8,6 +8,7 @@ endif
>>>>>>     obj-$(CONFIG_NET_DSA_LANTIQ_GSWIP) += lantiq_gswip.o
>>>>>>     obj-$(CONFIG_NET_DSA_MT7530_COMMON) += mt7530.o
>>>>>>     obj-$(CONFIG_NET_DSA_MT7530)    += mt7530-mdio.o
>>>>>> +obj-$(CONFIG_NET_DSA_MT7988)    += mt7530-mmio.o
>>>>>
>>>>> I'm not fond of this way. Wouldn't it be better if we split the mdio and
>>>>> mmio drivers to separate modules and kept switch hardware support on
>>>>> mt7530.c?
>>>>
>>>> You mean this in terms of Kconfig symbols?
>>>> Because the way you describe is basically what I'm doing here:
>>>>    * mt7530.c is the shared/common switch hardware driver
>>>>    * mt7530-mdio.c contains the MDIO accessors and MDIO device drivers for
>>>>      MT7530, MT7531, MT7621, MT7623, ...
>>>>    * mt7530-mmio.c contains the platform device driver for in-SoC switches
>>>>      which are accessed via MMIO, ie. MT7988 (and yes, this could be
>>>>      extended to also support MT7620A/N).
>>>
>>> Ok great.
>>>
>>>>
>>>> In early drafts I also named the Kconfig symbols
>>>> CONFIG_NET_DSA_MT7530 for mt7530.c (ie. the common part)
>>>> CONFIG_NET_DSA_MT7530_MDIO for the MDIO driver
>>>> CONFIG_NET_DSA_MT7530_MMIO for the MMIO driver
>>>>
>>>> However, as existing kernel configurations expect
>>>> CONFIG_NET_DSA_MT7530 to
>>>> select the MDIO driver, I decided it would be better to hide the
>>>> symbol of
>>>> the common part and have CONFIG_NET_DSA_MT7530 select the MDIO
>>>> driver like
>>>> it was before.
>>>
>>> You can "imply NET_DSA_MT7530_MDIO" from NET_DSA_MT7530 so the MDIO
>>> driver is also enabled when NET_DSA_MT7530 is selected. For example, on
>>> Realtek, both MDIO and SMI drivers are enabled by default when either of
>>> the main drivers are selected.
>>>
>>> config NET_DSA_MT7530
>>>       tristate "MediaTek MT7530 and MT7531 Ethernet switch support"
>>>       select NET_DSA_TAG_MTK
>>>       select MEDIATEK_GE_PHY
>>>       select PCS_MTK_LYNXI
>>>       imply NET_DSA_MT7530_MDIO
>>>       imply NET_DSA_MT7530_MMIO
>>
>> The final kconfig should look like this:
>>
>> config NET_DSA_MT7530
>> 	tristate "MediaTek MT7530 and MT7531 Ethernet switch support"
>> 	select NET_DSA_TAG_MTK
>> 	select MEDIATEK_GE_PHY
>> 	select PCS_MTK_LYNXI
>> 	imply NET_DSA_MT7530_MDIO
>> 	imply NET_DSA_MT7530_MMIO
>> 	help
>> 	  This enables support for the MediaTek MT7530 and MT7531 Ethernet
>> 	  switch chips. Multi-chip module MT7530 in MT7621AT, MT7621DAT,
>> 	  MT7621ST and MT7623AI SoCs, and built-in switch in MT7688 SoC is
>                                                               ^^^^^^
> You probably meant MT7988.
> 
> The built-in Fast Ethernet switch of older Ralink SoCs as well as MT7628 and
> MT7688 is a whole different story:
> https://github.com/stroese/linux/blob/gardena-v5.5/drivers/net/dsa/mt7628-esw.c

Yup, typo. "is" at the end should also be "are".

Arınç