Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri, 30 Dec 2022 15:32:24 +0200
From:   Ioana Ciornei <ioana.ciornei@nxp.com>
To:     Sean Anderson <sean.anderson@seco.com>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Russell King <linux@armlinux.org.uk>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>
Subject: Re: [PATCH net] net: dpaa2-mac: Get serdes only for backplane links
Message-ID: <20221230101710.btdw227v62nnj3le@skbuf>
References: <20221227230918.2440351-1-sean.anderson@seco.com>
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20221227230918.2440351-1-sean.anderson@seco.com>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?2jz7N+b++05iA1PFVhjHb/c4O+vaKTiR/xLNizG4bMiXy9DrXUK6BktCb2Pa?=
 =?us-ascii?Q?v7YIuer0db1z9z2IAbVc0P/TXjGQnScDHDL3BRYhPBoYpgi8r4xI7zCW4c+a?=
 =?us-ascii?Q?qCizALHVBeSvnmSSsvcs6Yik5H5Vd97JWUXHI8qsK+rDv/Ewb0ERDRdmU4+v?=
 =?us-ascii?Q?iAeALLE0IwbrTbmNAsjvzBzIvrk/lXNd8BgcgroY3Oq6eP9/JF2of01TnNCy?=
 =?us-ascii?Q?U1uMAgA8G3fkyUDI3J5W79/KrOhmxdF+aB56IxquJssJVBCRm66UCQLkH6Z8?=
 =?us-ascii?Q?pfhAaKS0VyflGeD7PfNdU2vTmHuZztTcXqSPMfeZLn+JaFS6ZzM0SCUlTK0M?=
 =?us-ascii?Q?b17q8lEyHvA6MI1zY7W8C2XbaeiOaIBcy/gVhVURC80WiA7TU/2lqodCMopH?=
 =?us-ascii?Q?uYUcywAYU0EaO6nvWlOH6AAIbFDbRgAxXpy4zXfNuF6zKbnR0T9siHrHhxEG?=
 =?us-ascii?Q?VBBTDCHb+eQowSv26VWzGYjuuJSH0tK8oFKXgc36X5awjsUlZp82oQlFp/ZW?=
 =?us-ascii?Q?IF4dMNstYrSk2Yllda+5gOiIXz5dY5nqR2NCpGMOXZwiSp/t/TQWhuFvWt5T?=
 =?us-ascii?Q?6TgOLiZlfAtR5l4Z/8Ecc6OJo9EQrbjd86uirUiyGZSN/iCmGkhCaNNIyNgr?=
 =?us-ascii?Q?l8HmUvAm5tVjYA/v/BKDn5USz0ymYI7YaLqfH4Z1B6uJVyvkOouf+2ydAlzR?=
 =?us-ascii?Q?7yjtsz2W8VppU1HNUBMy+fzLiapE9e/7C0Di3r5UsxKwNk1eH5LB6cooIddD?=
 =?us-ascii?Q?ICoYZ9sBP+XnD6caRzCCIQj+/kZVUWmEvVIIJpMaqp4Cr8gbssElHAiq7Je3?=
 =?us-ascii?Q?1y470Yyhmm8nrM4BE2chfGZGwPPXGRj4mYtxOVKBCMqVv3B221UNFEW4MhxP?=
 =?us-ascii?Q?b1awII081HgkLDrqfdeR7v8LPHd1Mu3fSxpxSdDM/NkCz0MAzwSA0VJpfVn7?=
 =?us-ascii?Q?r4Zhn/pZe8mPW9Yc8GN7kDyksPBZA18F92tBBswWiNry810MbvaByxLpxk39?=
 =?us-ascii?Q?Qb+vx5oezxSWH4FXDdYZa4W0QPZCf67yEJ4BlJSDyV+8Rs1CrngeDuXTMwQa?=
 =?us-ascii?Q?F1EdrkpgIVJX1aZUiBWV53SRDBWIO/aalARf55yNfOZ+NfA2Yzu1O7Soxjew?=
 =?us-ascii?Q?MckX3ewfw2vNaI0rJfntUxnIrVkjc/5njZsGLN+mLwFRl4fz1J6JzY1esGL4?=
 =?us-ascii?Q?U3Rdwp4KNsXjEuvmvpAPfjSNqlHcniC2MgohHsFlnFRuu86nYIbIn0sH7ygQ?=
 =?us-ascii?Q?tAyi2WYClvnEnLETHSjiUdLVBzZLdXHi3zbIJRSpy9nZT+7PwmyWuToFJDax?=
 =?us-ascii?Q?dG87/uiusv22J1AWGMMqgHsIAmCf+gu2ds0cZzImz7mhoqAyeNMQ5YNi+2SQ?=
 =?us-ascii?Q?lEiygCcTzVxOl3UpxeQbRLqy7+Wpze3DaY7gNyLiSa4i23TtcC5P6mGPb8Ol?=
 =?us-ascii?Q?3qTJEOwN0D8xQplVMZB0PN1EGGlIygLYC9nVryf3hVB3jv6RM1/HtcbUmu5b?=
 =?us-ascii?Q?SD5KjXKzmmnzZUuubcYvvKymyT2jU77/oK4InRgV8xm90YZirr6MIMba6lD2?=
 =?us-ascii?Q?qf5FjIKR6ZjUllgPChz+eVhHnd6u/bHNC2L4R9gs?=
X-OriginatorOrg: nxp.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 655fd58e-c278-4454-1874-08daea6a4c0c
X-MS-Exchange-CrossTenant-AuthSource: GV1PR04MB9055.eurprd04.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Dec 2022 13:32:29.7313
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: MchzOg+cJH1fPxcKyHhOPJkeOv5w6kHbgrt1+yADyONVWXrnCDPVRdM23OuT4L93MnHLOVaqFePSsxlbmAH6mA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM8PR04MB7473
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS autolearn=ham
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi Sean,

On Tue, Dec 27, 2022 at 06:09:18PM -0500, Sean Anderson wrote:
> When commenting on what would become commit 085f1776fa03 ("net: dpaa2-mac:
> add backplane link mode support"), Ioana Ciornei said [1]:
> 
> > ...DPMACs in TYPE_BACKPLANE can have both their PCS and SerDes managed
> > by Linux (since the firmware is not touching these). That being said,
> > DPMACs in TYPE_PHY (the type that is already supported in dpaa2-mac) can
> > also have their PCS managed by Linux (no interraction from the
> > firmware's part with the PCS, just the SerDes).
> 
> This implies that Linux only manages the SerDes when the link type is
> backplane. From my testing, the link fails to come up when the link type is
> phy, but does come up when it is backplane. Modify the condition in
> dpaa2_mac_connect to reflect this, moving the existing conditions to more
> appropriate places.
> 

What interface mode, firmware version etc are you testing on LS1088A?
Are you using the SerDes phy driver?

> [1] https://lore.kernel.org/netdev/20210120221900.i6esmk6uadgqpdtu@skbuf/
> 
> Fixes: f978fe85b8d1 ("dpaa2-mac: configure the SerDes phy on a protocol change")
> Signed-off-by: Sean Anderson <sean.anderson@seco.com>
> ---
> I tested this on an LS1088ARDB. I would appreciate if someone could
> verify that this doesn't break anything for the LX2160A.

I will test on a LX2160A but no sooner than next Tuesday. Sorry.

> 
>  drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
> index c886f33f8c6f..0693d3623a76 100644
> --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
> +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
> @@ -179,9 +179,13 @@ static void dpaa2_mac_config(struct phylink_config *config, unsigned int mode,
>  	if (err)
>  		netdev_err(mac->net_dev,  "dpmac_set_protocol() = %d\n", err);
>  
> -	err = phy_set_mode_ext(mac->serdes_phy, PHY_MODE_ETHERNET, state->interface);
> -	if (err)
> -		netdev_err(mac->net_dev, "phy_set_mode_ext() = %d\n", err);
> +	if (!phy_interface_mode_is_rgmii(mode)) {
> +		err = phy_set_mode_ext(mac->serdes_phy, PHY_MODE_ETHERNET,
> +				       state->interface);
> +		if (err)
> +			netdev_err(mac->net_dev, "phy_set_mode_ext() = %d\n",
> +				   err);
> +	}
>  }

This check is not necessary. Just above the snippet shown here is:

	if (!mac->serdes_phy)
		return;

And the 'serdes_phy' is only setup if the interface mode is not a rgmii.
	if (mac->features & DPAA2_MAC_FEATURE_PROTOCOL_CHANGE &&
	    !phy_interface_mode_is_rgmii(mac->if_mode) &&
	    is_of_node(dpmac_node)) {
		serdes_phy = of_phy_get(to_of_node(dpmac_node), NULL);
		
		if (serdes_phy == ERR_PTR(-ENODEV))
			serdes_phy = NULL;
		else if (IS_ERR(serdes_phy))
			return PTR_ERR(serdes_phy);
		else
			phy_init(serdes_phy);
	}
	mac->serdes_phy = serdes_phy;


>  
>  static void dpaa2_mac_link_up(struct phylink_config *config,
> @@ -317,7 +321,8 @@ static void dpaa2_mac_set_supported_interfaces(struct dpaa2_mac *mac)
>  		}
>  	}
>  
> -	if (!mac->serdes_phy)
> +	if (!(mac->features & !DPAA2_MAC_FEATURE_PROTOCOL_CHANGE) ||
> +	    !mac->serdes_phy)
>  		return;
>  
>  	/* In case we have access to the SerDes phy/lane, then ask the SerDes
> @@ -377,8 +382,7 @@ int dpaa2_mac_connect(struct dpaa2_mac *mac)
>  		return -EINVAL;
>  	mac->if_mode = err;
>  
> -	if (mac->features & DPAA2_MAC_FEATURE_PROTOCOL_CHANGE &&
> -	    !phy_interface_mode_is_rgmii(mac->if_mode) &&
> +	if (mac->attr.link_type == DPMAC_LINK_TYPE_BACKPLANE &&
>  	    is_of_node(dpmac_node)) {
>  		serdes_phy = of_phy_get(to_of_node(dpmac_node), NULL);
>  

If the goal is to restrict the serdes_phy setup only if in _BACKPLANE
mode, then why not just add another restriction here directly?

What I mean is not to remove any checks from this if statement but
rather add another one. And this would be the only change needed.


Ioana