Re: [PATCH v2 7/7] dt-bindings: net: dsa: mediatek,mt7530: update binding description

From: "Arınç ÜNAL" <arinc.unal@arinc9.com>
To: Rob Herring <robh@kernel.org>
Cc: "Andrew Lunn" <andrew@lunn.ch>,
	"Vivien Didelot" <vivien.didelot@gmail.com>,
	"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>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"Sean Wang" <sean.wang@mediatek.com>,
	"Landen Chao" <Landen.Chao@mediatek.com>,
	"DENG Qingfang" <dqfext@gmail.com>,
	"Frank Wunderlich" <frank-w@public-files.de>,
	"Luiz Angelo Daros de Luca" <luizluca@gmail.com>,
	"Sander Vanheule" <sander@svanheule.net>,
	"René van Dorst" <opensource@vdorst.com>,
	"Daniel Golle" <daniel@makrotopia.org>,
	erkin.bozoglu@xeront.com,
	"Sergio Paracuellos" <sergio.paracuellos@gmail.com>,
	netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 7/7] dt-bindings: net: dsa: mediatek,mt7530: update binding description
Date: Wed, 17 Aug 2022 00:53:33 +0300	[thread overview]
Message-ID: <112f47d9-5b8a-8be5-52da-42f7c5223161@arinc9.com> (raw)
In-Reply-To: <20220816212558.GA2754986-robh@kernel.org>

On 17.08.2022 00:25, Rob Herring wrote:
> On Sat, Aug 13, 2022 at 06:44:15PM +0300, Arınç ÜNAL wrote:
>> Update the description of the binding.
>>
>> - Describe the switches, which SoCs they are in, or if they are standalone.
>> - Explain the various ways of configuring MT7530's port 5.
>> - Remove phy-mode = "rgmii-txid" from description. Same code path is
>> followed for delayed rgmii and rgmii phy-mode on mtk_eth_soc.c.
>>
>> Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
>> ---
>>   .../bindings/net/dsa/mediatek,mt7530.yaml     | 97 ++++++++++++-------
>>   1 file changed, 62 insertions(+), 35 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml b/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
>> index 530ef5a75a2f..cf6340d072df 100644
>> --- a/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
>> +++ b/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
>> @@ -13,41 +13,68 @@ maintainers:
>>     - Sean Wang <sean.wang@mediatek.com>
>>   
>>   description: |
>> -  Port 5 of mt7530 and mt7621 switch is muxed between:
>> -  1. GMAC5: GMAC5 can interface with another external MAC or PHY.
>> -  2. PHY of port 0 or port 4: PHY interfaces with an external MAC like 2nd GMAC
>> -     of the SOC. Used in many setups where port 0/4 becomes the WAN port.
>> -     Note: On a MT7621 SOC with integrated switch: 2nd GMAC can only connected to
>> -       GMAC5 when the gpios for RGMII2 (GPIO 22-33) are not used and not
>> -       connected to external component!
>> -
>> -  Port 5 modes/configurations:
>> -  1. Port 5 is disabled and isolated: An external phy can interface to the 2nd
>> -     GMAC of the SOC.
>> -     In the case of a build-in MT7530 switch, port 5 shares the RGMII bus with 2nd
>> -     GMAC and an optional external phy. Mind the GPIO/pinctl settings of the SOC!
>> -  2. Port 5 is muxed to PHY of port 0/4: Port 0/4 interfaces with 2nd GMAC.
>> -     It is a simple MAC to PHY interface, port 5 needs to be setup for xMII mode
>> -     and RGMII delay.
>> -  3. Port 5 is muxed to GMAC5 and can interface to an external phy.
>> -     Port 5 becomes an extra switch port.
>> -     Only works on platform where external phy TX<->RX lines are swapped.
>> -     Like in the Ubiquiti ER-X-SFP.
>> -  4. Port 5 is muxed to GMAC5 and interfaces with the 2nd GAMC as 2nd CPU port.
>> -     Currently a 2nd CPU port is not supported by DSA code.
>> -
>> -  Depending on how the external PHY is wired:
>> -  1. normal: The PHY can only connect to 2nd GMAC but not to the switch
>> -  2. swapped: RGMII TX, RX are swapped; external phy interface with the switch as
>> -     a ethernet port. But can't interface to the 2nd GMAC.
>> -
>> -    Based on the DT the port 5 mode is configured.
>> -
>> -  Driver tries to lookup the phy-handle of the 2nd GMAC of the master device.
>> -  When phy-handle matches PHY of port 0 or 4 then port 5 set-up as mode 2.
>> -  phy-mode must be set, see also example 2 below!
>> -  * mt7621: phy-mode = "rgmii-txid";
>> -  * mt7623: phy-mode = "rgmii";
>> +  There are two versions of MT7530, standalone and in a multi-chip module.
>> +
>> +  MT7530 is a part of the multi-chip module in MT7620AN, MT7620DA, MT7620DAN,
>> +  MT7620NN, MT7621AT, MT7621DAT, MT7621ST and MT7623AI SoCs.
>> +
>> +  MT7530 in MT7620AN, MT7620DA, MT7620DAN and MT7620NN SoCs has got 10/100 PHYs
> 
> s/got //

Can't use British English on bindings? :)

> 
>> +  and the switch registers are directly mapped into SoC's memory map rather than
>> +  using MDIO. There is currently no support for this.
> 
> No support in the binding or driver? Driver capabilities are relevant to
> the binding.

In the driver. Also, did you mean irrelevant? Should I remove this part 
from the binding?

> 
>> +
>> +  There is only the standalone version of MT7531.
>> +
>> +  Port 5 on MT7530 has got various ways of configuration.
> 
> s/got //
> 
>> +
>> +  For standalone MT7530:
>> +
>> +    - Port 5 can be used as a CPU port.
>> +
>> +    - PHY 0 or 4 of the switch can be muxed to connect to the gmac of the SoC
>> +      which port 5 is wired to. Usually used for connecting the wan port
>> +      directly to the CPU to achieve 2 Gbps routing in total.
>> +
>> +      The driver looks up the reg on the ethernet-phy node which the phy-handle
>> +      property refers to on the gmac node to mux the specified phy.
>> +
>> +      The driver requires the gmac of the SoC to have "mediatek,eth-mac" as the
>> +      compatible string and the reg must be 1. So, for now, only gmac1 of an
>> +      MediaTek SoC can benefit this. Banana Pi BPI-R2 suits this.
>> +      Check out example 5 for a similar configuration.
>> +
>> +    - Port 5 can be wired to an external phy. Port 5 becomes a DSA slave.
>> +      Check out example 7 for a similar configuration.
>> +
>> +  For multi-chip module MT7530:
>> +
>> +    - Port 5 can be used as a CPU port.
>> +
>> +    - PHY 0 or 4 of the switch can be muxed to connect to gmac1 of the SoC.
>> +      Usually used for connecting the wan port directly to the CPU to achieve 2
>> +      Gbps routing in total.
>> +
>> +      The driver looks up the reg on the ethernet-phy node which the phy-handle
>> +      property refers to on the gmac node to mux the specified phy.
>> +
>> +      For the MT7621 SoCs, rgmii2 group must be claimed with rgmii2 function.
>> +      Check out example 5.
>> +
>> +    - In case of an external phy wired to gmac1 of the SoC, port 5 must not be
>> +      enabled.
>> +
>> +      In case of muxing PHY 0 or 4, the external phy must not be enabled.
>> +
>> +      For the MT7621 SoCs, rgmii2 group must be claimed with rgmii2 function.
>> +      Check out example 6.
>> +
>> +    - Port 5 can be muxed to an external phy. Port 5 becomes a DSA slave.
>> +      The external phy must be wired TX to TX to gmac1 of the SoC for this to
>> +      work. Ubiquiti EdgeRouter X SFP is wired this way.
>> +
>> +      Muxing PHY 0 or 4 won't work when the external phy is connected TX to TX.
>> +
>> +      For the MT7621 SoCs, rgmii2 group must be claimed with gpio function.
>> +      Check out example 7.
>>   
>>   properties:
>>     compatible:
>> -- 
>> 2.34.1
>>
>>