linux-kernel - Re: [PATCH net 3/4] net: bcmgenet: soft reset 40nm EPHYs before MAC init

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Date:   Wed, 16 Oct 2019 20:53:54 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Doug Berger <opendmb@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        bcm-kernel-feedback-list@...adcom.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 3/4] net: bcmgenet: soft reset 40nm EPHYs before MAC
 init



On 10/16/2019 4:06 PM, Doug Berger wrote:
> It turns out that the "Workaround for putting the PHY in IDDQ mode"
> used by the internal EPHYs on 40nm Set-Top Box chips when powering
> down puts the interface to the GENET MAC in a state that can cause
> subsequent MAC resets to be incomplete.
> 
> Rather than restore the forced soft reset when powering up internal
> PHYs, this commit moves the invocation of phy_init_hw earlier in
> the MAC initialization sequence to just before the MAC reset in the
> open and resume functions. This allows the interface to be stable
> and allows the MAC resets to be successful.
> 
> The bcmgenet_mii_probe() function is split in two to accommodate
> this. The new function bcmgenet_mii_connect() handles the first
> half of the functionality before the MAC initialization, and the
> bcmgenet_mii_config() function is extended to provide the remaining
> PHY configuration following the MAC initialization.
> 
> Fixes: 484bfa1507bf ("Revert "net: bcmgenet: Software reset EPHY after power on"")
> Signed-off-by: Doug Berger <opendmb@...il.com>

Acked-by: Florian Fainelli <f.fainelli@...il.com>

We will have to see how difficult it might be to back port towards
stable trees of interest, hopefully not too difficult.
-- 
Florian