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Date:   Mon, 16 Jan 2023 10:53:49 +0000
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     =?iso-8859-1?Q?Cl=E9ment_L=E9ger?= <clement.leger@bootlin.com>
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Subject: Re: [PATCH net-next 3/6] net: stmmac: start phylink before setting
 up hardware
Message-ID: <Y8UsvREsKOR2ejzT@shell.armlinux.org.uk>
References: <20230116103926.276869-1-clement.leger@bootlin.com>
 <20230116103926.276869-4-clement.leger@bootlin.com>
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Sender: Russell King (Oracle) <linux@armlinux.org.uk>
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On Mon, Jan 16, 2023 at 11:39:23AM +0100, Cl?ment L?ger wrote:
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index f2247b8cf0a3..88c941003855 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -3818,6 +3818,12 @@ static int __stmmac_open(struct net_device *dev,
>  		}
>  	}
>  
> +	/* We need to setup the phy & PCS before accessing the stmmac registers
> +	 * because in some cases (RZ/N1), if the stmmac IP is not clocked by the
> +	 * PCS, hardware init will fail because it lacks a RGMII RX clock.
> +	 */
> +	phylink_start(priv->phylink);

So what happens if you end up with the mac_link_up method being called
at this point in the driver, before the hardware has been setup ?

If you use a fixed-link, that's a real possibility.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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