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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10906C433EF for ; Tue, 7 Dec 2021 19:27:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231209AbhLGTbN (ORCPT ); Tue, 7 Dec 2021 14:31:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229953AbhLGTbN (ORCPT ); Tue, 7 Dec 2021 14:31:13 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE613C061574 for ; Tue, 7 Dec 2021 11:27:42 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 56BDCCE1B8B for ; Tue, 7 Dec 2021 19:27:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E03EC341C3; Tue, 7 Dec 2021 19:27:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638905258; bh=q9A1mg6NXYBeu6gzXlhPTl6VrlE0d9NlhaNb0JTmOus=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LAPb6tBuN9bOMr12xXdaFCMzX7iBCU9Qnf0/AtYKt04KA2ifUBenIXHARewa38xux QNyhYZl9zQWj7vZJej9Hmqq9S0wLY+jvO71RGKNHrP/Rf+gMmz62jeIMgjT8osW+Jv R3kR1oZKishOdd8wtmonSLnICpcoUBTLws1lxCeOHeh95YEyW67fZ5s0ulaI2JdOxt f1+f2Q3TRrWrGKoVrjc6CxGMgSZSsPnoi2xCwYL9JGDiE7iuRuoicanm4Sfa8gTnzs 88h0iB7PRZOQQAGG7x82grZI3vPiN/tPY0HIjt9gGBpq8NNgiAxfmiq3MJ5jJPnMg5 dBp8DObebQMgw== Date: Tue, 7 Dec 2021 20:27:33 +0100 From: Marek =?UTF-8?B?QmVow7pu?= To: Holger Brunck , Andrew Lunn Cc: netdev@vger.kernel.org, Jakub Kicinski Subject: Re: [v3 2/2] dsa: mv88e6xxx: make serdes SGMII/Fiber output amplitude configurable Message-ID: <20211207202733.56a0cf15@thinkpad> In-Reply-To: <20211207190730.3076-2-holger.brunck@hitachienergy.com> References: <20211207190730.3076-1-holger.brunck@hitachienergy.com> <20211207190730.3076-2-holger.brunck@hitachienergy.com> X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 7 Dec 2021 20:07:30 +0100 Holger Brunck wrote: > The mv88e6352, mv88e6240 and mv88e6176 have a serdes interface. This pat= ch > allows to configure the output swing to a desired value in the > devicetree node of the port. As the chips only supports eight dedicated > values we return EINVAL if the value in the DTS does not match. >=20 > CC: Andrew Lunn > CC: Jakub Kicinski > CC: Marek Beh=C3=BAn > Signed-off-by: Holger Brunck Holger, Andrew, there is another issue with this, which I only realized yesterday. What if the different amplitude needs to be set only for certain SerDes modes? I am bringing this up because I discovered that on Turris Mox we need to increase SerDes output amplitude when A3720 SOC is connected directly to 88E6141 switch, but only for 2500base-x mode. For 1000base-x, the default amplitude is okay. (Also when the SOC is connected to 88E6190, the amplitude does not need to be changed at all.) I plan to solve this in the comphy driver, not in device-tree. But if the solution is to be done in DTS, shouldn't there be a possibility to define the amplitude for a specific serdes mode only? For example serdes-2500base-x-tx-amplitude-millivolt or serdes-tx-amplitude-millivolt-2500base-x or serdes-tx-amplitude-millivolt,2500base-x ? What do you think? Marek