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 A2489EB64DC for ; Mon, 3 Jul 2023 13:50:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230426AbjGCNuA (ORCPT ); Mon, 3 Jul 2023 09:50:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229719AbjGCNt7 (ORCPT ); Mon, 3 Jul 2023 09:49:59 -0400 Received: from sender4-op-o15.zoho.com (sender4-op-o15.zoho.com [136.143.188.15]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84186109 for ; Mon, 3 Jul 2023 06:49:58 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1688392179; cv=none; d=zohomail.com; s=zohoarc; b=SP9ImYKJXEf65WKqag/ju5y526ZfAFIBV4itRdPacBQ3+yv5KnCru8ASuO9Hlo1Gt2oK5OjGfBVUSMXqhHesfFw44l8G58ol9rDbTZs4DUmr2mNbiu8R7n5wTKI8SpMtNvhTnFheLb4J/UW25OjOE1YUX+l1vx5BFFQaQfHSCDs= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1688392179; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:To; bh=0juxJGr0V0mWBkxuSy/zAkO1ju2c9SqaUoNVC94Ta+g=; b=DX6QQuBCyOLO33f2JL3SPON+PDyKnDqY1eJlK7uslPKmFb4TRsfiJgmyoGAQztmM7A8PKEZK+FLdZdB8gsIsKBIY7lsV6kcJNwhVBuvbkVjUmHLbEUBwrCT7wWyc8/wZWC1zStk5lUGlH6HoxgGCe+XO8Lghe/GrXoaadX9RSFw= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=linux.beauty; spf=pass smtp.mailfrom=me@linux.beauty; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1688392178; s=zmail; d=linux.beauty; i=me@linux.beauty; h=Date:Date:From:From:To:To:Cc:Cc:Message-ID:In-Reply-To:References:Subject:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-Id:Reply-To; bh=0juxJGr0V0mWBkxuSy/zAkO1ju2c9SqaUoNVC94Ta+g=; b=HWnuovJb6yqvdgTAK2CNyPNMuAPlm0fFmH8WjjDVWS0zulM3dFFROXLQSFR/CqSV SmRDdJwch6aB7hRBeuhgl35fz65Jn4i+LDo+6X6IBx8lnPlgfa1Pq9/V20UT1owcSFJ WugwavBR6h6CxjQqQP3VeKrrITPPXzcFwAyMXimw= Received: from mail.zoho.com by mx.zohomail.com with SMTP id 1688392177737939.3774690465508; Mon, 3 Jul 2023 06:49:37 -0700 (PDT) Date: Mon, 03 Jul 2023 21:49:37 +0800 From: Li Chen To: "Achal Verma" Cc: "Vignesh Raghavendra" , "Tom Joseph" , "Lorenzo Pieralisi" , "Krzysztof Wilczy_ski" , "Rob Herring" , "Bjorn Helgaas" , "linux-omap" , "linux-pci" , "linux-arm-kernel" , "linux-kernel" Message-ID: <1891c041807.fea67a55448140.3454059194195387266@linux.beauty> In-Reply-To: <20230703112914.68806-1-a-verma1@ti.com> References: <20230703112914.68806-1-a-verma1@ti.com> Subject: Re: [PATCH] PCI: j721e: Fix delay before PERST# deassert MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Importance: Medium User-Agent: Zoho Mail X-Mailer: Zoho Mail Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? Regards, Li