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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E7EF0C0015E for ; Tue, 1 Aug 2023 17:25:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=FbH5447I14tIAEtVSTjnCsPwZXLDlpN7oiCAFi3cfhA=; b=2wsYXpzwmmc/6n Lp62/BWRd6rftCLIwr1QyC6SuV+/ZSdTOPTohwYHkBWOYknkb7wODRidqIOPQK/zGSXgyCeI5n19R uf8yYjwOeWb3oB1hn56+MzpE/VX6U4EUucbX1iVDxnpThb8/22FbaI3C6AjSHwGf+muGGggKNSj42 f0b9LsCSu57DnvTQlV6DsMvO2L8LRiGWw+MZj6FHeYiKizCLeah8F20zh8Ta6iRCq/W1WyYdXPFom M3ozlOjKd8ayEPPl31EVBT0U3EQ0+GcnaoawEmfCUOuGqZbvpgztgpiPB0kZTjjSIuCoW9VP8loTA bEgeM/3Pcvt+mfFWQ9cg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qQt7D-002uwM-0S; Tue, 01 Aug 2023 17:24:59 +0000 Received: from [2001:4d48:ad52:32c8:5054:ff:fe00:142] (helo=pandora.armlinux.org.uk) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qQt7A-002uvC-0T; Tue, 01 Aug 2023 17:24:58 +0000 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=fSeYJzEj8ugDKym/LYhUtnwbOItQowiA5McP3oRnz3s=; b=gchVGUoEsMMGrN5/riaJ/YYQvV gGAWofDzZ7ctBzhw59ZyBSga3Om4UHPn4ijM4kfLqcn10Y1buTK67cxaSlIbR08dONMpUcNul4U6q I/okyaC5ARX2/u4rlfr/+P1/a1PlJ56wsHBZoaELQc7x51cftUw2jpHg5M/WgrBDs8KLbYMuhiu7N nbi1+C+P74jf+OTdayEBpI2miFe0cExbqfUJC3tFT1VJBUIQS7ece072lRVhwnLPk5mcqIOy7PiF9 kVXRF7oDaWR+AI6YhdbsdL8XIOurZpch6Nab1CI2lpIUWdI6O3cKO1I93lbya2lbda2XBu4M1pgNz 6K1PBa7Q==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:49744) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1qQt6h-0004QQ-23; Tue, 01 Aug 2023 18:24:27 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1qQt6c-0000sn-J6; Tue, 01 Aug 2023 18:24:22 +0100 Date: Tue, 1 Aug 2023 18:24:22 +0100 From: "Russell King (Oracle)" To: Shenwei Wang Cc: Johannes Zink , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Shawn Guo , Sascha Hauer , Neil Armstrong , Kevin Hilman , Vinod Koul , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Giuseppe Cavallaro , Alexandre Torgue , Jose Abreu , Pengutronix Kernel Team , Fabio Estevam , dl-linux-imx , Jerome Brunet , Martin Blumenstingl , Bhupesh Sharma , Nobuhiro Iwamatsu , Simon Horman , Andrew Halaney , Bartosz Golaszewski , Wong Vee Khee , Revanth Kumar Uppala , Jochen Henneberg , "netdev@vger.kernel.org" , "linux-stm32@st-md-mailman.stormreply.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-amlogic@lists.infradead.org" , "imx@lists.linux.dev" , Frank Li Subject: Re: [EXT] Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause the TXC clock in fixed-link Message-ID: References: <20230731161929.2341584-1-shenwei.wang@nxp.com> <20230731161929.2341584-3-shenwei.wang@nxp.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230801_102456_183407_7F35C8C4 X-CRM114-Status: GOOD ( 29.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Aug 01, 2023 at 05:06:46PM +0000, Shenwei Wang wrote: > > On Tue, Aug 01, 2023 at 02:47:46PM +0200, Johannes Zink wrote: > > > Hi Shenwei, > > > > > > thanks for your patch. > > > > > > On 7/31/23 18:19, Shenwei Wang wrote: > > > > When using a fixed-link setup, certain devices like the SJA1105 > > > > require a small pause in the TXC clock line to enable their internal > > > > tunable delay line (TDL). > > > > > > If this is only required for some devices, is it safe to enforce this > > > behaviour unconditionally for any kind of fixed link devices connected > > > to the MX93 EQOS or could this possibly break for other devices? > > > > This same point has been raised by Andrew Halaney in message-id > > <4govb566nypifbtqp5lcbsjhvoyble5luww3onaa2liinboguf@4kgihys6vhrg> > > and Fabio Estevam in message-id > > > > > com> > > but we don't seem to have any answer for it. > > > Hi Russell, > > I hope you have thoroughly read all of my earlier responses, as I believe I already addressed this question. > I'm happy to clarify further, but kindly avoid unsubstantiated comments. > > https://lore.kernel.org/imx/20230727152503.2199550-1-shenwei.wang@nxp.com/T/#m08da3797a056d4d8ea4c1d8956b445ae967e7cfa > " Yes, that's the purpose because it won't hurt even the other side is not SJA1105." So, why not include the answer in the commit message given that you've had to answer it several times already? > > Also, the patch still uses wmb() between the write and the delay, and as Will > > Deacon pointed out in his message, message-id > > <20230728153611.GH21718@willie-the-truck> > > this is not safe, yet still a new version was sent. > > > > Can we conclude that even without the wmb() here, the desired delay time between > operations can still be ensured? How did you come to that conclusion? I see no further discussion after I raised this, Will replied, and you suggested a read-back. However, that isn't what you've implemented on v3, you've gone back to what looks like the original code in v2 which brought up this question - and Will indicated it was _unsafe_. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel