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Subject: Re: [PATCH net-next v2 2/3] dt-bindings: dp83td510: Add binding for
 DP83TD510 Ethernet PHY
To:     Andrew Lunn <andrew@lunn.ch>
CC:     <davem@davemloft.net>, <f.fainelli@gmail.com>,
        <hkallweit1@gmail.com>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
References: <20201020171221.730-1-dmurphy@ti.com>
 <20201020171221.730-3-dmurphy@ti.com> <20201020185601.GJ139700@lunn.ch>
 <20201020190717.GK139700@lunn.ch>
From:   Dan Murphy <dmurphy@ti.com>
Message-ID: <331e3c73-38ca-3224-c682-5ed3a4ed9f73@ti.com>
Date:   Tue, 20 Oct 2020 14:14:17 -0500
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Andrew

On 10/20/20 2:07 PM, Andrew Lunn wrote:
>> Humm. Are 1v and 2.4v advertised so it can be auto negotiated? Maybe a
>> PHY tunable is not correct? Is this voltage selection actually more
>> like pause and EEE?
> [Goes and looks at the datasheet]
>
> Register 0x20E, bit 13:
>
> 1 = Advertise that the 10BASE-T1L PHY has increased transmit/
> receive level ability
> 0 = Do not advertise that the 10BASE-T1L PHY has increased
> transmit/receive level ability (default)
>
> So does this mean 2.4v?

This can also be strapped to a certain voltage level.  The device may 
not have the regulators on board to drive a 2.4v signal. 1v signal AVDD 
is 1.8v and 2.4v the AVDD needs to be at least 3.3v


This Strap defines the voltage level
requested by PHY during auto
negotiation. It is reflected in bit 12 of
0x20E. While using Force mode for
Linkup, the strap controls the output
voltage and reflects in bit 12 of 0x18F6

Bit 12

1 = Enable 2.4 Vpp operating mode
0 = Enable 1.0 Vpp operating mode

So maybe this is a hybrid of tunable for master/slave and a DT for 
voltage level since the ability of the board to drive the signal can vary.

Dan


>   	Andrew