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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 EACA7C433ED for ; Wed, 5 May 2021 20:40:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B770B613E6 for ; Wed, 5 May 2021 20:40:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234855AbhEEUlQ (ORCPT ); Wed, 5 May 2021 16:41:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:48958 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234566AbhEEUlP (ORCPT ); Wed, 5 May 2021 16:41:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 31733613E9; Wed, 5 May 2021 20:40:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620247218; bh=sqlBJeP2BuEGyy+j2+DoZweK1T+0pBp8HGXOCvNJaVc=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=e0ZdQzW323cvRis2z39theMLvgGcGhr1aRJdgJ+M+dyFQUK6B3neoJM7cRga3yDFA jZlEk/JbmihCRj3Mmctzvjjx6Nrf8zLT4+WEm5fvBuo3LR4H5ap9G4EsZ4zhbB112D q3bYplfp/mXVhEavQHjhtyHzsZkljyP6cQ4dPKCYmbF4hRgQFM6FuT6oj3L8m8Z97i pv1FJ13BnC/KQt8aNoPiQ1Wa3ljmayTEZTr+ap8QeeslviimkgBRahFOaU2k1XDI2S iVksPKXzeQGfLQjSaOJOWC+nWnTqJdjtyIJ1B3ov98JN4RVLxmFn6AQrgotZCSA/Wi vHwxDLv9gnJqw== Date: Wed, 5 May 2021 15:40:16 -0500 From: Bjorn Helgaas To: Alex Williamson Cc: Amey Narkhede , Oliver O'Halloran , Shanker R Donthineni , Bjorn Helgaas , linux-pci , Linux Kernel Mailing List , Sinan Kaya , Vikram Sethi Subject: Re: [PATCH v4 2/2] PCI: Enable NO_BUS_RESET quirk for Nvidia GPUs Message-ID: <20210505204016.GA1330808@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210505131357.07e55042@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Wed, May 05, 2021 at 01:13:57PM -0600, Alex Williamson wrote: > On Wed, 5 May 2021 23:10:32 +0530 > Amey Narkhede wrote: > > On 21/05/05 01:56PM, Oliver O'Halloran wrote: > > > On Wed, May 5, 2021 at 12:50 PM Bjorn Helgaas wrote: > > > > On Mon, May 03, 2021 at 09:07:11PM -0500, Shanker R Donthineni wrote: > > > > > On 5/3/21 5:42 PM, Bjorn Helgaas wrote: > > > > > > Obviously _RST only works for built-in devices, since there's no AML > > > > > > for plug-in devices, right? So if there's a plug-in card with this > > > > > > GPU, neither SBR nor _RST will work? > > > > > These are not plug-in PCIe GPU cards, will exist on upcoming server > > > > > baseboards. ACPI-reset should wok for plug-in devices as well as long > > > > > as firmware has _RST method defined in ACPI-device associated with > > > > > the PCIe hot-plug slot. > > > > > > > > Maybe I'm missing something, but I don't see how _RST can work for > > > > plug-in devices. _RST is part of the system firmware, and that > > > > firmware knows nothing about what will be plugged into the slot. So > > > > if system firmware supplies _RST that knows how to reset the Nvidia > > > > GPU, it's not going to do the right thing if you plug in an NVMe > > > > device instead. > > > > > > > > Can you elaborate on how _RST would work for plug-in devices? > > I'm not sure I really understand these concerns about plug-in devices. I'm not really concerned about plug-in devices. Shanker said above that _RST would work for them: ACPI-reset should work for plug-in devices as well as long as firmware has _RST method defined in ACPI-device associated with the PCIe hot-plug slot. and I disagreed. _RST *cannot* work for plug-in devices because firmware doesn't know what device will be plugged in and therefore cannot provide the required device-specific _RST. That's all I wanted to clarify. Bjorn