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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 35C76C49361 for ; Mon, 14 Jun 2021 05:58:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E982613C2 for ; Mon, 14 Jun 2021 05:58:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232385AbhFNGAP (ORCPT ); Mon, 14 Jun 2021 02:00:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229696AbhFNGAG (ORCPT ); Mon, 14 Jun 2021 02:00:06 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E261DC061574; Sun, 13 Jun 2021 22:58:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=rUu+qFDot8hQHtf4FhxEOy4uPBeisgSjqsgw/gq3pTw=; b=MmXSpV1qTF9D+jdt3BP3Wcc3mr X4hZ1T+tVjQSHtjXlHQntyV5xGYNkpNsey8Q7KNb3u2+felb5qWeYXTznyrHDRrR1uTAGQlLRAEi4 HMFbMaAGNYO/84p3z/Mc9z2UCqEuNcTi7uhX4L+s9M0qJGjtDuA1dgb6gmbvyX/UMUYGx036MKC/L ekWawu+m1tOVMFmF7ngg6+IHoYTRcdYYSgKjygWus0dMKBRWapLXncYL5LL61OGR6p3+gcuyKBqLX AD2dtIDqp4Lbk2cKJHdHQyT3OWV4gBbEAg0wKds4eW4absMkVjPxwBdIQK1KwL8QNI6DolQvWTXP+ +mqdWCAQ==; Received: from hch by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lsfbN-0054Jy-03; Mon, 14 Jun 2021 05:57:39 +0000 Date: Mon, 14 Jun 2021 06:57:36 +0100 From: Christoph Hellwig To: Dongdong Liu Cc: helgaas@kernel.org, hch@infradead.org, kw@linux.com, linux-pci@vger.kernel.org, rajur@chelsio.com, hverkuil-cisco@xs4all.nl, linux-media@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [RESEND PATCH V3 6/6] PCI: Enable 10-Bit tag support for PCIe RP devices Message-ID: References: <1623576555-40338-1-git-send-email-liudongdong3@huawei.com> <1623576555-40338-7-git-send-email-liudongdong3@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1623576555-40338-7-git-send-email-liudongdong3@huawei.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, Jun 13, 2021 at 05:29:15PM +0800, Dongdong Liu wrote: > PCIe spec 5.0r1.0 section 2.2.6.2 implementation note, In configurations > where a Requester with 10-Bit Tag Requester capability needs to target > multiple Completers, one needs to ensure that the Requester sends 10-Bit > Tag Requests only to Completers that have 10-Bit Tag Completer capability. > So we enable 10-Bit Tag Requester for root port only when the devices > under the root port support 10-Bit Tag Completer. > > Signed-off-by: Dongdong Liu > --- > drivers/pci/pcie/portdrv_pci.c | 75 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 75 insertions(+) > > diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c > index c7ff1ee..baf413f 100644 > --- a/drivers/pci/pcie/portdrv_pci.c > +++ b/drivers/pci/pcie/portdrv_pci.c > @@ -90,6 +90,78 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = { > #define PCIE_PORTDRV_PM_OPS NULL > #endif /* !PM */ > > +static int pci_10bit_tag_comp_support(struct pci_dev *dev, void *data) > +{ > + u8 *support = data; > + > + if (*support == 0) > + return 0; > + > + if (!pci_is_pcie(dev)) { > + *support = 0; > + return 0; > + } > + > + /* > + * PCIe spec 5.0r1.0 section 2.2.6.2 implementation note. > + * For configurations where a Requester with 10-Bit Tag Requester > + * capability targets Completers where some do and some do not have > + * 10-Bit Tag Completer capability, how the Requester determines which > + * NPRs include 10-Bit Tags is outside the scope of this specification. > + * So we do not consider hotplug scenario. > + */ > + if (dev->is_hotplug_bridge) { > + *support = 0; > + return 0; > + } > + > + if (!(dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_COMP)) { > + *support = 0; > + return 0; > + } > + > + return 0; > +} > + > +static void pci_configure_rp_10bit_tag(struct pci_dev *dev) > +{ > + u8 support = 1; > + struct pci_dev *pchild; > + > + if (dev->subordinate == NULL) > + return; > + > + /* If no devices under the root port, no need to enable 10-Bit Tag. */ > + pchild = list_first_entry_or_null(&dev->subordinate->devices, > + struct pci_dev, bus_list); > + if (pchild == NULL) > + return; pchild is never used after this check, so this could be simplified to a list_empty(&dev->subordinate->devices).