From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E381C3A5A3 for ; Tue, 27 Aug 2019 16:13:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20A7D2186A for ; Tue, 27 Aug 2019 16:13:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="zoV9sB08" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728972AbfH0QNZ (ORCPT ); Tue, 27 Aug 2019 12:13:25 -0400 Received: from vps0.lunn.ch ([185.16.172.187]:34982 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726539AbfH0QNY (ORCPT ); Tue, 27 Aug 2019 12:13:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=EUdcOXqzDMg/BPMZ+mHA3Lf8aib/qAEj7QKintG8i1o=; b=zoV9sB08UoCM+TTqsh2QC+T5y+ lZz1Ib+zNYLNZRXVPOm2DbrZuZSMep/zbGNMPAsR7DBWL3PjE0xYRuVSiCMWWrT9paWu+58hqLWYK BeT4BvV4LrCDclJaiVCpjNqloDVf7Yaooj0FbOSeQq/jYcfdbQfLo98KAgBObxacyNmk=; Received: from andrew by vps0.lunn.ch with local (Exim 4.89) (envelope-from ) id 1i2dig-0004bz-PJ; Tue, 27 Aug 2019 17:49:18 +0200 Date: Tue, 27 Aug 2019 17:49:18 +0200 From: Andrew Lunn To: "Voon, Weifeng" Cc: Florian Fainelli , "David S. Miller" , Maxime Coquelin , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Jose Abreu , Heiner Kallweit , "Ong, Boon Leong" Subject: Re: [PATCH v1 net-next] net: phy: mdio_bus: make mdiobus_scan also cover PHY that only talks C45 Message-ID: <20190827154918.GO2168@lunn.ch> References: <1566870769-9967-1-git-send-email-weifeng.voon@intel.com> <20190826185418.GG2168@lunn.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Aug 27, 2019 at 03:23:34PM +0000, Voon, Weifeng wrote: > > > > Make mdiobus_scan() to try harder to look for any PHY that only > > talks C45. > > > If you are not using Device Tree or ACPI, and you are letting the MDIO > > > bus be scanned, it sounds like there should be a way for you to > > > provide a hint as to which addresses should be scanned (that's > > > mii_bus::phy_mask) and possibly enhance that with a mask of possible > > > C45 devices? > > > > Yes, i don't like this unconditional c45 scanning. A lot of MDIO bus > > drivers don't look for the MII_ADDR_C45. They are going to do a C22 > > transfer, and maybe not mask out the MII_ADDR_C45 from reg, causing an > > invalid register write. Bad things can then happen. > > > > With DT and ACPI, we have an explicit indication that C45 should be used, > > so we know on this platform C45 is safe to use. We need something > > similar when not using DT or ACPI. > > > > Andrew > > Florian and Andrew, > The mdio c22 is using the start-of-frame ST=01 while mdio c45 is using ST=00 > as identifier. So mdio c22 device will not response to mdio c45 protocol. > As in IEEE 802.1ae-2002 Annex 45A.3 mention that: > " Even though the Clause 45 MDIO frames using the ST=00 frame code > will also be driven on to the Clause 22 MII Management interface, > the Clause 22 PHYs will ignore the frames. " > > Hence, I am not seeing any concern that the c45 scanning will mess up with > c22 devices. Hi Voon Take for example mdio-hisi-femac.c static int hisi_femac_mdio_read(struct mii_bus *bus, int mii_id, int regnum) { struct hisi_femac_mdio_data *data = bus->priv; int ret; ret = hisi_femac_mdio_wait_ready(data); if (ret) return ret; writel((mii_id << BIT_PHY_ADDR_OFFSET) | regnum, data->membase + MDIO_RWCTRL); There is no check here for MII_ADDR_C45. So it will perform a C22 transfer. And regnum will still have MII_ADDR_C45 in it, so the writel() is going to set bit 30, since #define MII_ADDR_C45 (1<<30). What happens on this hardware under these conditions? You cannot unconditionally ask an MDIO driver to do a C45 transfer. Some drivers are going to do bad things. Andrew