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 77A8EEB64DC for ; Mon, 3 Jul 2023 14:44:49 +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-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:CC:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=eIONz7yK9w69D3s1BhC54ev+W9AV5cVcKt9FxTpcnQo=; b=KObKL4dt7q4di4 C/xSZOwoBXop2ErCf+MHOwSH4wQC/tMVOWrxDYFSHLasxy89aQf8orG3+xtSr+uWoHI1e+WsXRSEJ e72zsI2suZ+PRlBjiwgXQdtmEQSMHwmJI8pwjzbVcXJv9/uAr3cNO8yShfnYDstKuF0g36pr0M2Dy F0sFUET96qviTaCxyrOIDv2LY6ETJs2+DjbxjRK7RPsrUIPP0YONt3bJKw6D5keOU9GOmn3QEtuWK l/g44qpIhcDhDAGBdt+QreleAX9mh760x6NLRisLeJCo0CU6wPgKYD2dLovVUM19EtnRTij3hWrGI wlVgduq0LEqZqD+MROaw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qGKmr-00Am7j-08; Mon, 03 Jul 2023 14:44:21 +0000 Received: from lelv0142.ext.ti.com ([198.47.23.249]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qGKmo-00Am6o-1R for linux-arm-kernel@lists.infradead.org; Mon, 03 Jul 2023 14:44:20 +0000 Received: from lelv0266.itg.ti.com ([10.180.67.225]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id 363Ei0xv066266; Mon, 3 Jul 2023 09:44:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1688395440; bh=EdzWHkf1aaa1WsMyIhRj6KpzRSMZEp4+Px5Tx9YAjRc=; h=Date:Subject:To:CC:References:From:In-Reply-To; b=Cvvw45rNa5ezhkvHMcuAWc10NurKwUE0HvRjTSWMMydmmGgNiC9nA3YLRrzIyJFdY NlSwqwbVA9Y9NOs0iSbXPAqYPkQUcXfDDXoyd5meDrFMeXhNi4x62gsXcLOtHIWj5U XbcIun2TTAZKUjKi414Oyqoz19IflfDE4HfMfPL4= Received: from DFLE115.ent.ti.com (dfle115.ent.ti.com [10.64.6.36]) by lelv0266.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 363Ei0i7034089 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 3 Jul 2023 09:44:00 -0500 Received: from DFLE103.ent.ti.com (10.64.6.24) by DFLE115.ent.ti.com (10.64.6.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.23; Mon, 3 Jul 2023 09:43:59 -0500 Received: from fllv0040.itg.ti.com (10.64.41.20) by DFLE103.ent.ti.com (10.64.6.24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.23 via Frontend Transport; Mon, 3 Jul 2023 09:43:59 -0500 Received: from [10.249.128.37] (ileaxei01-snat2.itg.ti.com [10.180.69.6]) by fllv0040.itg.ti.com (8.15.2/8.15.2) with ESMTP id 363Eht6L097671; Mon, 3 Jul 2023 09:43:56 -0500 Message-ID: <9bb176c9-f1e6-349e-5486-74e0ea6b5012@ti.com> Date: Mon, 3 Jul 2023 20:13:55 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [EXTERNAL] Re: [PATCH] PCI: j721e: Fix delay before PERST# deassert Content-Language: en-US To: Li Chen CC: Vignesh Raghavendra , Tom Joseph , Lorenzo Pieralisi , Krzysztof Wilczy_ski , Rob Herring , Bjorn Helgaas , linux-omap , linux-pci , linux-arm-kernel , linux-kernel References: <20230703112914.68806-1-a-verma1@ti.com> <1891c041807.fea67a55448140.3454059194195387266@linux.beauty> From: "Verma, Achal" In-Reply-To: <1891c041807.fea67a55448140.3454059194195387266@linux.beauty> X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230703_074418_690381_9D68833E X-CRM114-Status: UNSURE ( 9.40 ) X-CRM114-Notice: Please train this message. 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/3/2023 7:19 PM, Li Chen wrote: > Hi Achal, > ---- On Mon, 03 Jul 2023 19:29:14 +0800 Achal Verma wrote --- > > As per the PCIe Card Electromechanical specification REV. 3.0, PERST# > > signal should be de-asserted after minimum 100ms from the time power-rails > > become stable. Current delay of 100us is observed to be not enough on some > > custom platform implemented using TI's K3 SOCs. > > > > So, to ensure 100ms delay to give sufficient time for power-rails and > > refclk to become stable, change delay from 100us to 100ms. > > What problems could arise if the delay is too small? Would some endpoints not be able to detect it? If delay is small, cpu stall is reported during probe() while accessing PCIe registers in some cases. > > Regards, > Li _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel