netdev - Re: [PATCH] net: sh_eth: fix mdio access in sh_eth

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Message-ID: <0ab08e61-833d-1d9e-ef71-311964854d46@cogentembedded.com>
Date:   Wed, 15 May 2019 18:41:22 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH] net: sh_eth: fix mdio access in sh_eth_close() for some
 SoCs

Hello!

   It's not "some SoCs", it's only R-Car gen2 and RZ/G1 SoCs.

On 05/15/2019 08:36 AM, Yoshihiro Shimoda wrote:

> The sh_eth_close() resets the MAC and then calls phy_stop()
> so that mdio read access result is incorrect without any error
> according to kernel trace like below:
> 
> ifconfig-216   [003] .n..   109.133124: mdio_access: ee700000.ethernet-ffffffff read  phy:0x01 reg:0x00 val:0xffff

   Not sure how RMII mode affects the MDIO transfers...

> To fix the issue, this patch adds a condition and set the RMII mode
> regiseter in sh_eth_dev_exit() for some SoCs.
> 
> Note that when I have tried to move the sh_eth_dev_exit() calling
> after phy_stop() on sh_eth_close(), but it gets worse.

   Ah, I was going to suggest changing the call order... what happens then?

> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
> ---
>  drivers/net/ethernet/renesas/sh_eth.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
> index e33af37..106ae90 100644
> --- a/drivers/net/ethernet/renesas/sh_eth.c
> +++ b/drivers/net/ethernet/renesas/sh_eth.c
> @@ -1596,6 +1596,10 @@ static void sh_eth_dev_exit(struct net_device *ndev)
>  
>  	/* Set MAC address again */
>  	update_mac_address(ndev);
> +
> +	/* Set the mode again if required */

   Should be "RMII mode", n ot just "Mode". We prolly need more detailed explanation...

> +	if (mdp->cd->rmiimode)
> +		sh_eth_write(ndev, 0x1, RMIIMODE);
>  }
>  
>  static void sh_eth_rx_csum(struct sk_buff *skb)

MBR, Sergei