linux-kernel - Re: [PATCH net-next v2 20/21] net: ravb: Do not apply RX CSUM settings to hardware if the interface is down

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Date: Sat, 16 Dec 2023 23:36:31 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Claudiu <claudiu.beznea@...on.dev>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<richardcochran@...il.com>, <p.zabel@...gutronix.de>,
	<yoshihiro.shimoda.uh@...esas.com>, <wsa+renesas@...g-engineering.com>,
	<geert+renesas@...der.be>
CC: <netdev@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Claudiu Beznea
	<claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH net-next v2 20/21] net: ravb: Do not apply RX CSUM
 settings to hardware if the interface is down

On 12/14/23 2:45 PM, Claudiu wrote:

> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> Do not apply the RX CSUM settings to hardware if the interface is down. In
> case runtime PM is enabled, and while the interface is down, the IP will be
> in reset mode (as for some platforms disabling/enabling the clocks will
> switch the IP to standby mode, which will lead to losing registers'

   To/From perhaps?
   And just "register".

> content) and applying settings in reset mode is not an option. Instead,
> cache the RX CSUM settings and apply them in ravb_open().

   Have this issue actually occurred for you?

> Commit prepares for the addition of runtime PM.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
[...]

> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 633346b6cd7c..9ff943dff522 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1868,6 +1868,15 @@ static int ravb_open(struct net_device *ndev)
>  	if (info->gptp || info->ccc_gac)
>  		ravb_ptp_init(ndev, priv->pdev);
>  
> +	/* Apply features that might have been changed while the interface
> +	 * was down.
> +	 */
> +	if (ndev->hw_features & NETIF_F_RXCSUM) {

   I'm afraid this is a wrong field; we need ndev->features, no?

> +		u32 val = (ndev->features & NETIF_F_RXCSUM) ? ECMR_RCSC : 0;
> +
> +		ravb_modify(ndev, ECMR, ECMR_RCSC, val);
> +	}
> +

   The ECMR setting is already done in ravb_emac_init_rcar(), no need
to duplicate it here, I think...

>  	/* PHY control start */
>  	error = ravb_phy_start(ndev);
>  	if (error)
> @@ -2337,6 +2346,9 @@ static void ravb_set_rx_csum(struct net_device *ndev, bool enable)
>  	struct ravb_private *priv = netdev_priv(ndev);
>  	unsigned long flags;
>  
> +	if (!netif_running(ndev))

   Racy as well...

> +		return;
> +

   Hm, sh_eth.c doesn't have such check -- perhaps should be fixed
as well...

[...]

MBR, Sergey