netdev - Re: [PATCH v4.1] phylib: Add device reset GPIO support

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Date:   Mon, 4 Dec 2017 17:20:13 +0100
From:   Richard Leitner <richard.leitner@...data.com>
To:     Geert Uytterhoeven <geert+renesas@...der.be>,
        "David S . Miller" <davem@...emloft.net>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Simon Horman <horms@...ge.net.au>,
        Magnus Damm <magnus.damm@...il.com>
CC:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        <netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-renesas-soc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4.1] phylib: Add device reset GPIO support


On 12/04/2017 01:35 PM, Geert Uytterhoeven wrote:
> From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
> 
> The PHY devices sometimes do have their reset signal (maybe even power
> supply?) tied to some GPIO and sometimes it also does happen that a boot
> loader does not leave it deasserted. So far this issue has been attacked
> from (as I believe) a wrong angle: by teaching the MAC driver to manipulate
> the GPIO in question; that solution, when applied to the device trees, led
> to adding the PHY reset GPIO properties to the MAC device node, with one
> exception: Cadence MACB driver which could handle the "reset-gpios" prop
> in a PHY device subnode. I believe that the correct approach is to teach
> the 'phylib' to get the MDIO device reset GPIO from the device tree node
> corresponding to this device -- which this patch is doing...
> 
> Note that I had to modify the AT803x PHY driver as it would stop working
> otherwise -- it made use of the reset GPIO for its own purposes...
> 
> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
> Acked-by: Rob Herring <robh@...nel.org>
> [geert: Propagate actual errors from fwnode_get_named_gpiod()]
> [geert: Avoid destroying initial setup]
> [geert: Consolidate GPIO descriptor acquiring code]
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---

Successfully tested this patch on a i.MX6SOLO based board containing a
LAN8710 PHY:

Tested-by: Richard Leitner <richard.leitner@...data.com>