linux-kernel - Re: [PATCH net-next 3/3] net: fec: reset phy on resume after power-up

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Date:   Tue, 14 Dec 2021 19:54:54 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Philippe Schenker <philippe.schenker@...adex.com>
Cc:     netdev@...r.kernel.org, Joakim Zhang <qiangqing.zhang@....com>,
        "David S . Miller" <davem@...emloft.net>,
        Russell King <linux@...linux.org.uk>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Francesco Dolcini <francesco.dolcini@...adex.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Fabio Estevam <festevam@...il.com>,
        Fugang Duan <fugang.duan@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 3/3] net: fec: reset phy on resume after power-up

On Tue, Dec 14, 2021 at 01:16:38PM +0100, Philippe Schenker wrote:
> Reset the eth PHY after resume in case the power was switched off
> during suspend, this is required by some PHYs if the reset signal
> is controlled by software.
> 
> Signed-off-by: Philippe Schenker <philippe.schenker@...adex.com>
> 
> ---
> 
>  drivers/net/ethernet/freescale/fec_main.c | 1 +

Hi Philippe

What i don't particularly like about this is that the MAC driver is
doing it. Meaning if this PHY is used with any other MAC, the same
code needs adding there.

Is there a way we can put this into phylib? Maybe as part of
phy_init_hw()? Humm, actually, thinking aloud:

int phy_init_hw(struct phy_device *phydev)
{
	int ret = 0;

	/* Deassert the reset signal */
	phy_device_reset(phydev, 0);

So maybe in the phy driver, add a suspend handler, which asserts the
reset. This call here will take it out of reset, so applying the reset
you need?

   Andrew