Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH net-next v4 2/4] dt-bindings: net: Add Rx/Tx output
 configuration for 10base T1L
To:     Andrew Lunn <andrew@lunn.ch>
CC:     <davem@davemloft.net>, <f.fainelli@gmail.com>,
        <hkallweit1@gmail.com>, <robh@kernel.org>,
        <ciorneiioana@gmail.com>, <devicetree@vger.kernel.org>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <20201117201555.26723-1-dmurphy@ti.com>
 <20201117201555.26723-3-dmurphy@ti.com> <20201117203150.GA1800835@lunn.ch>
From:   Dan Murphy <dmurphy@ti.com>
Message-ID: <553087de-e6e4-23b9-e8c0-d77b430703f3@ti.com>
Date:   Tue, 17 Nov 2020 14:36:38 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20201117203150.GA1800835@lunn.ch>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Precedence: bulk

Andrew

On 11/17/20 2:31 PM, Andrew Lunn wrote:
> On Tue, Nov 17, 2020 at 02:15:53PM -0600, Dan Murphy wrote:
>> Per the 802.3cg spec the 10base T1L can operate at 2 different
>> differential voltages 1v p2p and 2.4v p2p. The abiility of the PHY to
> ability
Ack
>
>> drive that output is dependent on the PHY's on board power supply.
>> This common feature is applicable to all 10base T1L PHYs so this binding
>> property belongs in a top level ethernet document.
>>
>> Signed-off-by: Dan Murphy <dmurphy@ti.com>
>> ---
>>   Documentation/devicetree/bindings/net/ethernet-phy.yaml | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
>> index 6dd72faebd89..bda1ce51836b 100644
>> --- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml
>> +++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml
>> @@ -174,6 +174,12 @@ properties:
>>         PHY's that have configurable TX internal delays. If this property is
>>         present then the PHY applies the TX delay.
>>   
>> +  max-tx-rx-p2p-microvolt:
>> +    description: |
>> +      Configures the Tx/Rx p2p differential output voltage for 10base-T1L PHYs.
> Does it configure, or does it limit? I _think_ this is a negotiation
> parameter, so the PHY might decide to do 1100mV if the link peer is
> near by even when max-tx-rx-p2p-microvolt has the higher value.

For this device we can configure or force it to only work at 1.1v p2p 
otherwise 2.4 is the default.

But each LP's have to be configured for the same voltage. unless auto 
negotiation is on then it negotiates the voltage.

Dan

>
>       Andrew