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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 92014C433E6 for ; Mon, 15 Mar 2021 15:04:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6718A64E31 for ; Mon, 15 Mar 2021 15:04:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233430AbhCOPDz (ORCPT ); Mon, 15 Mar 2021 11:03:55 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35182 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238439AbhCOPDo (ORCPT ); Mon, 15 Mar 2021 11:03:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615820624; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tQS7ZiyS9Sed7OnVFwINJrQq7RX27EFmwFkt5eXsXEQ=; b=LLDMO9x9E/oo4iWq03tcg9cS8Uo513ue5+Imobpvf7yNLjPbx+Mpd32U5PSC3vWZMXXp2C kUk+Jl+S/YHrPR/EGvu31yZuhlR7YZrk94u2nit1zE6YhP0KaNONJDw4R7nqWQ6TxmqtWd qS/00aX1DaZSGJcF4o+wz4QpR27FIL4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-24-XCV0EwtfNp64fQlXQgaIqQ-1; Mon, 15 Mar 2021 11:03:42 -0400 X-MC-Unique: XCV0EwtfNp64fQlXQgaIqQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9E6EF1015C84; Mon, 15 Mar 2021 15:03:40 +0000 (UTC) Received: from x1.home.shazbot.org (ovpn-112-255.phx2.redhat.com [10.3.112.255]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2D44318A69; Mon, 15 Mar 2021 15:03:40 +0000 (UTC) Date: Mon, 15 Mar 2021 09:03:39 -0600 From: Alex Williamson To: Pali =?UTF-8?B?Um9ow6Fy?= Cc: Amey Narkhede , bhelgaas@google.com, raphael.norwitz@nutanix.com, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH 4/4] PCI/sysfs: Allow userspace to query and set device reset mechanism Message-ID: <20210315090339.54546e91@x1.home.shazbot.org> In-Reply-To: <20210315145238.6sg5deblr2z2pupu@pali> References: <20210312173452.3855-1-ameynarkhede03@gmail.com> <20210312173452.3855-5-ameynarkhede03@gmail.com> <20210314235545.girtrazsdxtrqo2q@pali> <20210315134323.llz2o7yhezwgealp@archlinux> <20210315135226.avwmnhkfsgof6ihw@pali> <20210315083409.08b1359b@x1.home.shazbot.org> <20210315145238.6sg5deblr2z2pupu@pali> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 15 Mar 2021 15:52:38 +0100 Pali Roh=C3=A1r wrote: > On Monday 15 March 2021 08:34:09 Alex Williamson wrote: > > On Mon, 15 Mar 2021 14:52:26 +0100 > > Pali Roh=C3=A1r wrote: > > =20 > > > On Monday 15 March 2021 19:13:23 Amey Narkhede wrote: =20 > > > > slot reset (pci_dev_reset_slot_function) and secondary bus > > > > reset(pci_parent_bus_reset) which I think are hot reset and > > > > warm reset respectively. =20 > > >=20 > > > No. PCI secondary bus reset =3D PCIe Hot Reset. Slot reset is just an= other > > > type of reset, which is currently implemented only for PCIe hot plug > > > bridges and for PowerPC PowerNV platform and it just call PCI seconda= ry > > > bus reset with some other hook. PCIe Warm Reset does not have API in > > > kernel and therefore drivers do not export this type of reset via any > > > kernel function (yet). =20 > >=20 > > Warm reset is beyond the scope of this series, but could be implemented > > in a compatible way to fit within the pci_reset_fn_methods[] array > > defined here. =20 >=20 > Ok! >=20 > > Note that with this series the resets available through > > pci_reset_function() and the per device reset attribute is sysfs remain > > exactly the same as they are currently. The bus and slot reset > > methods used here are limited to devices where only a single function is > > affected by the reset, therefore it is not like the patch you proposed > > which performed a reset irrespective of the downstream devices. This > > series only enables selection of the existing methods. Thanks, > >=20 > > Alex > > =20 >=20 > But with this patch series, there is still an issue with PCI secondary > bus reset mechanism as exported sysfs attribute does not do that > remove-reset-rescan procedure. As discussed in other thread, this reset > let device in unconfigured / broken state. No, there's not: int pci_reset_function(struct pci_dev *dev) { int rc; if (!dev->reset_fn) return -ENOTTY; pci_dev_lock(dev); >>> pci_dev_save_and_disable(dev); rc =3D __pci_reset_function_locked(dev); >>> pci_dev_restore(dev); pci_dev_unlock(dev); return rc; } The remove/re-scan was discussed primarily because your patch performed a bus reset regardless of what devices were affected by that reset and it's difficult to manage the scope where multiple devices are affected. Here, the bus and slot reset functions will fail unless the scope is limited to the single device triggering this reset. Thanks, Alex