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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89440C433F5 for ; Wed, 13 Oct 2021 22:13:01 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 251C061151 for ; Wed, 13 Oct 2021 22:13:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 251C061151 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linuxfoundation.org Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id E95FA60B16; Wed, 13 Oct 2021 22:13:00 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id VxscmdnusNIf; Wed, 13 Oct 2021 22:12:57 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp3.osuosl.org (Postfix) with ESMTPS id 547E560ADA; Wed, 13 Oct 2021 22:12:57 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 20046C000F; Wed, 13 Oct 2021 22:12:57 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9F6FCC000D for ; Wed, 13 Oct 2021 22:12:56 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 73D14833AF for ; Wed, 13 Oct 2021 22:12:56 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp1.osuosl.org (amavisd-new); dkim=pass (2048-bit key) header.d=kernel.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9O4cLfssYgpr for ; Wed, 13 Oct 2021 22:12:56 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp1.osuosl.org (Postfix) with ESMTPS id 11F2F82974 for ; Wed, 13 Oct 2021 22:12:55 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 5A64161151; Wed, 13 Oct 2021 22:12:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634163175; bh=u/bQLZfhgnTnBbANf/qHToPTgbfBAr7b4QRmI0DM+VQ=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=Pucg75TZ34Ae7T9jQ+XgW7e3rakhnRpGxYCSWvo2KxWvClG4ZbIKbtjeC2UVH+oO7 iVoNz/cLB6cSajRUNncbKcrPGbXD+ShoH15SzmVOLk+06vQmt6Z/lB063sUIpLOTmw R1laj0u3CVt86yKRk6JI9fS1kR5UQXiBp7dmZdRiInrPT8zKXLqikFm+SUZILmBlek 41SxPxZsmdwemO4Ok3cqgzGZGIl2UTjmWHhgRpCimk10jJ02LX/h899Uur3nfBbMeH coJjsSJGtt5f3YMjTcOCBHPuG+mnNeFJ3lz3CO5q4I8oPbVyKrgmbMtI3WATZIFq6J SQrjktw55/ahg== Date: Wed, 13 Oct 2021 17:12:53 -0500 From: Bjorn Helgaas To: Rob Herring Subject: Re: [PATCH 02/22] PCI: Unify PCI error response checking Message-ID: <20211013221253.GA1928518@bhelgaas> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: linux-kernel-mentees@lists.linuxfoundation.org, "linux-kernel@vger.kernel.org" , PCI , Bjorn Helgaas , Pali =?iso-8859-1?Q?Roh=E1r?= X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 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 Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" On Wed, Oct 13, 2021 at 04:47:43PM -0500, Rob Herring wrote: > Presumably, there could be some register somewhere where all 1s is > valid? So I think we need the error values. We have to assume ~0 is a valid value for any config registers except the few defined by the spec that have bits required to be 0. There can be all kinds of vendor-defined stuff in config space that can be anything. > Also, I seem to recall only the vendor/device IDs are defined to be > all 1s for non-existent devices. Other errors are undefined? I think this case is actually an instance of the PCI controller fabricating ~0 because a PCI/PCIe error occurred (I think on PCI it's a Master Abort when nothing responds; on PCIe the read terminates as an Unsupported Request (PCIe r5.0, sec 2.3.2)). _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees