netdev - Re: [PATCH net v2] net: phy: phy_ethtool_ksettings_set: Don't discard phy_start

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Message-ID: <e07b6b7c-3353-461e-887d-96be9a9f6f36@gmail.com>
Date:   Mon, 8 Nov 2021 19:01:23 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>, Bastian Germann <bage@...utronix.de>
Cc:     Benedikt Spranger <b.spranger@...utronix.de>,
        "Russell King (Oracle)" <linux@...linux.org.uk>,
        davem@...emloft.net, netdev@...r.kernel.org,
        Florian Fainelli <f.fainelli@...il.com>
Subject: Re: [PATCH net v2] net: phy: phy_ethtool_ksettings_set: Don't discard
 phy_start_aneg's return

On 08.11.2021 18:57, Andrew Lunn wrote:
>> It is BCM53125. Currently, you can set "mdix auto|off|on" which does
>> not take any effect.  The chip will do what is its default depending
>> on copper autonegotiation.
>>
>> I am adding support for setting "mdix auto|off". I want the thing to error on "mdix on".
>> Where would I add that check?
> 
> /* MDI or MDI-X status/control - if MDI/MDI_X/AUTO is set then
>  * the driver is required to renegotiate link
>  */
> #define ETH_TP_MDI_INVALID	0x00 /* status: unknown; control: unsupported */
> #define ETH_TP_MDI		0x01 /* status: MDI;     control: force MDI */
> #define ETH_TP_MDI_X		0x02 /* status: MDI-X;   control: force MDI-X */
> #define ETH_TP_MDI_AUTO		0x03 /*                  control: auto-select */
> 
> So there are three valid settings. And you are saying you only want to
> implement two of them? If the hardware can do all three, you should
> implement all three.
> 

If we would like to support PHY's that don't support all MDI modes then
supposedly this would require to add ETHTOOL_LINK_MODE bits for the
MDI modes. Then we could use the generic mechanism to check the bits in
the "supported" bitmap.

> 	  Andrew
> 
>