Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756585AbdCTSeY (ORCPT ); Mon, 20 Mar 2017 14:34:24 -0400 Received: from bastet.se.axis.com ([195.60.68.11]:44453 "EHLO bastet.se.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756394AbdCTSeS (ORCPT ); Mon, 20 Mar 2017 14:34:18 -0400 Subject: Re: [PATCH net-next] stmmac: call stmmac_init_phy from stmmac_dvr_probe To: Florian Fainelli , , , References: <20170320172915.8313-1-niklass@axis.com> <257f3b05-805d-fd59-5435-89ede6b0fe4b@gmail.com> CC: , From: Niklas Cassel Message-ID: <82fbc595-5269-bcd9-d75f-778fbd8d2bdb@axis.com> Date: Mon, 20 Mar 2017 19:34:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.6.0 MIME-Version: 1.0 In-Reply-To: <257f3b05-805d-fd59-5435-89ede6b0fe4b@gmail.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.0.5.60] X-ClientProxiedBy: XBOX02.axis.com (10.0.5.16) To XBOX02.axis.com (10.0.5.16) X-TM-AS-GCONF: 00 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2403 Lines: 54 On 03/20/2017 06:43 PM, Florian Fainelli wrote: > On 03/20/2017 10:29 AM, Niklas Cassel wrote: >> From: Niklas Cassel >> >> It is usually possible to do >> ethtool -s autoneg on >> so that you trigger an autoneg before calling >> ip link set dev eth0 up > This is completely driver specific and there is no guarantee for this to > work universally across all device drivers because when your interface > is brought down, the most sensible thing to expect in return is that > your PHY is powered down (unless your interface participates in > Wake-on-LAN). > >> However, stmmac returns -EBUSY if !netif_running. >> The only reason for this appears to be that stmmac_init_phy >> is called from stmmac_open instead of from stmmac_dvr_probe. >> >> Move stmmac_init_phy to stmmac_dvr_probe so that ethool >> works as soon as register_netdev has been called. >> stmmac_check_ether_addr was also moved to probe, >> so that the ordering doesn't change. > Are you sure this is a good idea? There are many drivers that moved the > PHY probe into ndo_open() for mainly two things: > > - phy_connect() starts the PHY state machine and starting the state > machine without a network device running is kind of wasting cycles > > - if the interface is probed, but not used, you are keeping the Ethernet > link running without being able to service packets, which is at best a > waste of power Hello Florian Thank you for your input. I can see the point in keeping phy_connect in ndo_open. What I dislike is the -EBUSY from stmmac_ethtool_get_link_ksettings, since this will create warnings in user space by our favorite monolith. (Please don't flame me, I dislike it as much as you guys.) [ WARNING ] systemd-udevd[236]: link_config: could not get ethtool features for eth0 [ WARNING ] systemd-udevd[236]: Could not set offload features of eth0: Device or resource busy However, it is kind of sad that drivers are so inconsistent of what goes in probe and what goes in ndo_open...which is tied together with the whole mess of when certain ethtool commands work or do not work. Do you know of a good way to avoid the -EBUSY in stmmac_ethtool_get_link_ksettings, but still keep phy_connect in ndo_open? The current code checks netif_running(), which checks __LINK_STATE_START, which gets set by __dev_open(). stmmac_ethtool_get_link_ksettings also returns -ENODEV if ndev->phydev == NULL.