linux-kernel - Re: [PATCH] net: mv643xx_eth: handle EPROBE

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Date:   Mon, 21 Feb 2022 13:21:49 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Mauri Sandberg <maukka@....kapsi.fi>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH] net: mv643xx_eth: handle EPROBE_DEFER

On Mon, Feb 21, 2022 at 08:24:41AM +0200, Mauri Sandberg wrote:
> Obtaining MAC address may be deferred in cases when the MAC is stored
> in NVMEM block and it may now be ready upon the first retrieval attempt
> returing EPROBE_DEFER. Handle it here and leave logic otherwise as it
> was.
> 
> Signed-off-by: Mauri Sandberg <maukka@....kapsi.fi>
> ---
>  drivers/net/ethernet/marvell/mv643xx_eth.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c
> index 105247582684..0694f53981f2 100644
> --- a/drivers/net/ethernet/marvell/mv643xx_eth.c
> +++ b/drivers/net/ethernet/marvell/mv643xx_eth.c
> @@ -2740,7 +2740,10 @@ static int mv643xx_eth_shared_of_add_port(struct platform_device *pdev,
>  		return -EINVAL;
>  	}
>  
> -	of_get_mac_address(pnp, ppd.mac_addr);
> +	ret = of_get_mac_address(pnp, ppd.mac_addr);
> +
> +	if (ret == -EPROBE_DEFER)
> +		return ret;

Hi Mauri

There appears to be a follow on issue. There can be multiple ports. So
it could be the first port does not use a MAC address from the NVMEM,
but the second one does. The first time in
mv643xx_eth_shared_of_add_port() is successful and a platform device
is added. The second port can then fail with -EPROBE_DEFER. That
causes the probe to fail, but the platform device will not be
removed. The next time the driver is probed, it will add a second
platform device for the first port, causing bad things to happen.

Please can you add code to remove the platform device when the probe
fails.

	Andrew