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[23.128.96.18]) by mx.google.com with ESMTP id nc2si2526038ejc.653.2021.03.31.11.36.57; Wed, 31 Mar 2021 11:37:19 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=fail (test mode) header.i=@armlinux.org.uk header.s=pandora-2019 header.b=jklEy7gQ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=armlinux.org.uk Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235111AbhCaSfu (ORCPT + 99 others); Wed, 31 Mar 2021 14:35:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234963AbhCaSfc (ORCPT ); Wed, 31 Mar 2021 14:35:32 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADB06C061574; Wed, 31 Mar 2021 11:35:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: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=0vZ+YaBhujkG/DFgqzNwjOQqJ1o921OtGFpttV4YyFA=; b=jklEy7gQzb5vBp/1CFBQ5AVcq /oFYyKdRqN9Rl+OvtwuysRz00/kEMHBShFHUsGGdF6cv5bavqD8FBjFZbBUgo5WUM6UCu/SPhIA1p SGUzcjKnGFwjwGzSb/iamfyr3bWWB52b9QrHpaqfCSMxyR90aJcCub2HVf3gI0EtA8QIV1aKywy0+ JTcnlbLL/gqf+aVyfidB7rrJ6p12jy0v4bSxF3rUcgv36NJtY6UacgW1H5Cn3eVETp/fKPFZlG/I3 fcdShUHEjsWtCUnPJDMZYhnugIFpVpjc1u0x+SakX9nc191u2htTCF8rsAC77XHu/jBGO4PsDVzhJ yoy/TpGIA==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:51982) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lRfgc-0002AN-Hp; Wed, 31 Mar 2021 19:35:26 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1lRfga-000489-Ja; Wed, 31 Mar 2021 19:35:24 +0100 Date: Wed, 31 Mar 2021 19:35:24 +0100 From: Russell King - ARM Linux admin To: danilokrummrich@dk-develop.de Cc: Andrew Lunn , davem@davemloft.net, hkallweit1@gmail.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jeremy.linton@arm.com Subject: Re: [PATCH 2/2] net: mdio: support c45 peripherals on c22 busses Message-ID: <20210331183524.GV1463@shell.armlinux.org.uk> References: <20210331141755.126178-1-danilokrummrich@dk-develop.de> <20210331141755.126178-3-danilokrummrich@dk-develop.de> <6f1dfc28368d098ace9564e53ed92041@dk-develop.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6f1dfc28368d098ace9564e53ed92041@dk-develop.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King - ARM Linux admin Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 31, 2021 at 07:58:33PM +0200, danilokrummrich@dk-develop.de wrote: > For this cited change the only thing happening is that if get_phy_device() > already failed for probing with is_c45==false (C22 devices) it tries to > probe with is_c45==true (C45 devices) which then either results into actual > C45 frame transfers or indirect accesses by calling mdiobus_c45_*() functions. Please explain why and how a PHY may not appear to be present using C22 frames to read the ID registers, but does appear to be present when using C22 frames to the C45 indirect registers - and summarise which PHYs have this behaviour. It seems very odd that any PHY would only implement C45 indirect registers in the C22 register space. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!