linux-kernel - RE: [PATCH 1/2] net: phy: Update get_phy_c45

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Message-ID: <DB5PR04MB1240A0F8E519D1BE168C1332EAFE0@DB5PR04MB1240.eurprd04.prod.outlook.com>
Date:   Wed, 24 May 2017 06:05:19 +0000
From:   Bogdan Purcareata <bogdan.purcareata@....com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/2] net: phy: Update get_phy_c45_ids for Cortina PHYs

> -----Original Message-----
> From: Florian Fainelli [mailto:f.fainelli@...il.com]
> Sent: Tuesday, May 23, 2017 9:12 PM
> To: Andrew Lunn <andrew@...n.ch>; Bogdan Purcareata
> <bogdan.purcareata@....com>
> Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 1/2] net: phy: Update get_phy_c45_ids for Cortina PHYs
> 
> On 05/23/2017 09:55 AM, Andrew Lunn wrote:
> >> The patches mentioned in the commit message add _some_ support for
> >> the Cortina PHYs - mainly checking for devices at additional
> >> locations. Once they are found, the phy IDs must be read from custom
> >> locations.
> >
> > As a general principle, we don't add hacks in generic code to handle
> > broken devices. We add generic mechanisms to work around the
> > brokenness.
> >
> > In this case, by using ethernet-phy-id in the device tree, we are
> > saying, this PHYs probing is totally borked, but we know it is there,
> > at this address. Just load the driver.
> >
> > Please try to make ethernet-phy-id work.
> 
> What Andrew is suggesting is to leverage the code in
> drivers/of/of_mdio.c which does the following:
> 
>        is_c45 = of_device_is_compatible(child,
>                                          "ethernet-phy-ieee802.3-c45");
> 
>         if (!is_c45 && !of_get_phy_id(child, &phy_id))
>                 phy = phy_device_create(mdio, addr, phy_id, 0, NULL);
>         else
>                 phy = get_phy_device(mdio, addr, is_c45);
>         if (IS_ERR(phy))
>                 return;
> 
> If you know the PHY ID, and you did put it in the PHY node's compatible
> string (in the format that of_get_phy_id() expects it to, and you also
> did not add "ethernet-phy-ieee802.3-c45") then the PHY library will
> directly create the PHY device, with the designated ID, at the specific
> address.
> 
> While this works for clause 22 PHYs, I don't know if it also does for
> clause 45 PHYs, but as Andrew is suggesting, I would be more inclined
> into making this scheme work for all types (22 or 45) PHYs, rather than
> hacking the core code that tries to identify devices in packages.
> 
> Can you give it a spin?

Sure. My first thought was to latch onto the codepath that had some mention of Cortina PHYs.

I will check of_get_phy_id() and see if it does the job.

Thank you!
Bogdan