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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 79A2FC63798 for ; Sat, 28 Nov 2020 21:57:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C709208CA for ; Sat, 28 Nov 2020 21:57:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="v/I6BXQI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387814AbgK1V4z (ORCPT ); Sat, 28 Nov 2020 16:56:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:33450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391367AbgK1VyB (ORCPT ); Sat, 28 Nov 2020 16:54:01 -0500 Received: from localhost (129.sub-72-107-112.myvzw.com [72.107.112.129]) (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 4125320857; Sat, 28 Nov 2020 21:53:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606600400; bh=cb7v+yyp8V0gUPgw13jOGxbQanmZsArHbf9RhiLHmkQ=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=v/I6BXQISl6Ls7lROR48qKflb9h8GOYNGn01hBKIQPrdztEdaDhr5HlS+t27DcZiJ F1tVSOJ7zOgvAqv/wdpRPqgzienFknj8JPkuEaK9ruE4kjEs3lHZ5CkLluihUBP5zy d/ur7M3eZOJF8fMdp7O/v/O1UxTISSiv7FqsZZK0= Date: Sat, 28 Nov 2020 15:53:18 -0600 From: Bjorn Helgaas To: "Kuppuswamy, Sathyanarayanan" Cc: ashok.raj@intel.com, knsathya@kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas , Olof Johansson Subject: Re: [PATCH 1/5] PCI/DPC: Ignore devices with no AER Capability Message-ID: <20201128215318.GA924062@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Sat, Nov 28, 2020 at 01:49:46PM -0800, Kuppuswamy, Sathyanarayanan wrote: > On 11/28/20 12:24 PM, Bjorn Helgaas wrote: > > On Wed, Nov 25, 2020 at 06:01:57PM -0800, Kuppuswamy, Sathyanarayanan wrote: > > > On 11/25/20 5:18 PM, Bjorn Helgaas wrote: > > > > From: Bjorn Helgaas > > > > > > > > Downstream Ports may support DPC regardless of whether they support AER > > > > (see PCIe r5.0, sec 6.2.10.2). Previously, if the user booted with > > > > "pcie_ports=dpc-native", it was possible for dpc_probe() to succeed even if > > > > the device had no AER Capability, but dpc_get_aer_uncorrect_severity() > > > > depends on the AER Capability. > > > > > > > > dpc_probe() previously failed if: > > > > > > > > !pcie_aer_is_native(pdev) && !pcie_ports_dpc_native > > > > !(pcie_aer_is_native() || pcie_ports_dpc_native) # by De Morgan's law > > > > > > > > so it succeeded if: > > > > > > > > pcie_aer_is_native() || pcie_ports_dpc_native > > > > > > > > Fail dpc_probe() if the device has no AER Capability. > > > > > > > > Signed-off-by: Bjorn Helgaas > > > > Cc: Olof Johansson > > > > --- > > > > drivers/pci/pcie/dpc.c | 3 +++ > > > > 1 file changed, 3 insertions(+) > > > > > > > > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c > > > > index e05aba86a317..ed0dbc43d018 100644 > > > > --- a/drivers/pci/pcie/dpc.c > > > > +++ b/drivers/pci/pcie/dpc.c > > > > @@ -287,6 +287,9 @@ static int dpc_probe(struct pcie_device *dev) > > > > int status; > > > > u16 ctl, cap; > > > > + if (!pdev->aer_cap) > > > > + return -ENOTSUPP; > > > Don't we check aer_cap support in drivers/pci/pcie/portdrv_core.c ? > > > > > > We don't enable DPC service, if AER service is not enabled. And AER > > > service is only enabled if AER capability is supported. > > > > > > So dpc_probe() should not happen if AER capability is not supported? > > > > I don't think that's always true. If I'm reading this right, we have > > this: > > > > get_port_device_capability(...) > > { > > #ifdef CONFIG_PCIEAER > > if (dev->aer_cap && ...) > > services |= PCIE_PORT_SERVICE_AER; > > #endif > > > > if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) && > > pci_aer_available() && > > (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER))) > > services |= PCIE_PORT_SERVICE_DPC; > > } > > > > and in the case where: > > > > - CONFIG_PCIEAER=y > > - booted with "pcie_ports=dpc-native" (pcie_ports_dpc_native is true) > > - "dev" has no AER capability > > - "dev" has DPC capability > > > > I think we do enable PCIE_PORT_SERVICE_DPC. > Got it. But further looking into it, I am wondering whether > we should keep this dependency? Currently we just use it to > dump the error information. Do we need to create dependency > between DPC and AER (which is functionality not dependent) just > to see more details about the error? That's a good question, but I don't really want to get into the actual operation of the AER and DPC drivers in this series, so maybe something we should explore later.