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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 65EF8C3A5A0 for ; Mon, 19 Aug 2019 19:24:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 395FD22DA7 for ; Mon, 19 Aug 2019 19:24:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566242684; bh=AP7Vdzra3NcppB0agbt0hGNputzUIfBO2Q8KFiwaX2Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=aE5SozThDIxgaHfkvMTPHGJdtjPzU7GbbE4RD5tALjwFoBQDnVrIPZbG5d8NvGeA8 FrDKvFl+VvVN5i10Z0lUOm7nXOIffJaijobskJeJWVfi37OS2UEY5dnwQbeKd8Xiid 0rz4a54QCgM4qd65oxAbT5SomJBsM1t1ToojJ35k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728317AbfHSTYn (ORCPT ); Mon, 19 Aug 2019 15:24:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:40728 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728315AbfHSTYn (ORCPT ); Mon, 19 Aug 2019 15:24:43 -0400 Received: from localhost (unknown [69.71.4.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 09FF1206C1; Mon, 19 Aug 2019 19:24:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566242682; bh=AP7Vdzra3NcppB0agbt0hGNputzUIfBO2Q8KFiwaX2Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=f4SO6OUPDs3akkK6X0jKRt3/uQXiwFsXxa+QmJFy+HqxrMbrbXzZCGeiE187Fjc+Z u7QhIt5LWmeR8hfrNg28WBiPEh6LJQjvi51U2/H5U+q03iWVOIINDqtXaL/7StXi6h Z8ieypqUVtUvhZW20m3AoFVdqdgsUPEKRtFA3CdQ= Date: Mon, 19 Aug 2019 14:24:40 -0500 From: Bjorn Helgaas To: "Z.q. Hou" Cc: "linux-pci@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "gustavo.pimentel@synopsys.com" , "jingoohan1@gmail.com" , "robh+dt@kernel.org" , "mark.rutland@arm.com" , "shawnguo@kernel.org" , Leo Li , "lorenzo.pieralisi@arm.com" , "M.h. Lian" Subject: Re: [PATCH 3/4] ARM: dts: ls1021a: Remove num-lanes property from PCIe nodes Message-ID: <20190819192440.GT253360@google.com> References: <20190812042435.25102-1-Zhiqiang.Hou@nxp.com> <20190812042435.25102-4-Zhiqiang.Hou@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190812042435.25102-4-Zhiqiang.Hou@nxp.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Mon, Aug 12, 2019 at 04:22:27AM +0000, Z.q. Hou wrote: > From: Hou Zhiqiang > > On FSL Layerscape SoCs, the number of lanes assigned to PCIe > controller is not fixed, it is determined by the selected > SerDes protocol in the RCW (Reset Configuration Word), and > the PCIe link training is completed automatically base on > the selected SerDes protocol, and the link width set-up is > updated by hardware. So the num-lanes is not needed to > specify the link width. > > The current num-lanes indicates the max lanes PCIe controller > can support up to, instead of the lanes assigned to the PCIe > controller. This can result in PCIe link training fail after > hot-reset. So remove the num-lanes to avoid set-up to incorrect > link width. It would be useful to explain *why* "num-lanes" in DT causes a link training failure. Maybe the code programs "num-lanes" somewhere, overriding what hardware automatically sensed? Maybe the code tries to bring up exactly "num-lanes" lanes even if not all are present? > Signed-off-by: Hou Zhiqiang > --- > arch/arm/boot/dts/ls1021a.dtsi | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/arm/boot/dts/ls1021a.dtsi b/arch/arm/boot/dts/ls1021a.dtsi > index 464df4290ffc..2f6977ada447 100644 > --- a/arch/arm/boot/dts/ls1021a.dtsi > +++ b/arch/arm/boot/dts/ls1021a.dtsi > @@ -874,7 +874,6 @@ > #address-cells = <3>; > #size-cells = <2>; > device_type = "pci"; > - num-lanes = <4>; > num-viewport = <6>; > bus-range = <0x0 0xff>; > ranges = <0x81000000 0x0 0x00000000 0x40 0x00010000 0x0 0x00010000 /* downstream I/O */ > @@ -899,7 +898,6 @@ > #address-cells = <3>; > #size-cells = <2>; > device_type = "pci"; > - num-lanes = <4>; > num-viewport = <6>; > bus-range = <0x0 0xff>; > ranges = <0x81000000 0x0 0x00000000 0x48 0x00010000 0x0 0x00010000 /* downstream I/O */ > -- > 2.17.1 >